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A line provides Wavelength in nanometers for “400,” “500,” “600,” and “700” nanometers. Within this line are all of the colors of the visible spectrum. Below this line, labeled from left to right are “Cosmic radiation,” “Gamma rays,” “X-rays,” “Ultraviolet,” then a small callout area for the line above containing the colors in the visual spectrum, followed by “Infrared,” “Terahertz radiation,” “Radar,” “Television and radio broadcasting,” and “AC circuits.”
Different wavelengths of light are associated with our perception of different colors. (credit: modification of work by Johannes Ahlmann)

Sound waves

Like light waves, the physical properties of sound waves are associated with various aspects of our perception of sound. The frequency of a sound wave is associated with our perception of that sound’s pitch    . High-frequency sound waves are perceived as high-pitched sounds, while low-frequency sound waves are perceived as low-pitched sounds. The audible range of sound frequencies is between 20 and 20000 Hz, with greatest sensitivity to those frequencies that fall in the middle of this range.

As was the case with the visible spectrum, other species show differences in their audible ranges. For instance, chickens have a very limited audible range, from 125 to 2000 Hz. Mice have an audible range from 1000 to 91000 Hz, and the beluga whale’s audible range is from 1000 to 123000 Hz. Our pet dogs and cats have audible ranges of about 70–45000 Hz and 45–64000 Hz, respectively (Strain, 2003).

The loudness of a given sound is closely associated with the amplitude of the sound wave. Higher amplitudes are associated with louder sounds. Loudness is measured in terms of decibels (dB) , a logarithmic unit of sound intensity. A typical conversation would correlate with 60 dB; a rock concert might check in at 120 dB ( [link] ). A whisper 5 feet away or rustling leaves are at the low end of our hearing range; sounds like a window air conditioner, a normal conversation, and even heavy traffic or a vacuum cleaner are within a tolerable range. However, there is the potential for hearing damage from about 80 dB to 130 dB: These are sounds of a food processor, power lawnmower, heavy truck (25 feet away), subway train (20 feet away), live rock music, and a jackhammer. The threshold for pain is about 130 dB, a jet plane taking off or a revolver firing at close range (Dunkle, 1982).

This illustration has a vertical bar in the middle labeled Decibels (dB) numbered 0 to 140 in intervals of 20 from the bottom to the top. To the left of the bar, the “sound intensity” of different sounds is labeled: “Hearing threshold” is 0; “Whisper” is 30, “soft music” is 40, “Risk of hearing loss” is 110, “pain threshold” is 130, and “harmful” is 140. To the right of the bar are photographs depicting “common sound”: At 20 decibels is a picture of rustling leaves; At 60 is two people talking, at 80 is a car, at 90 is a food processor, at 120 is a music concert, and at 130 are jets.
This figure illustrates the loudness of common sounds. (credit "planes": modification of work by Max Pfandl; credit "crowd": modification of work by Christian Holmér; credit "blender": modification of work by Jo Brodie; credit "car": modification of work by NRMA New Cars/Flickr; credit "talking": modification of work by Joi Ito; credit "leaves": modification of work by Aurelijus Valeiša)

Although wave amplitude is generally associated with loudness, there is some interaction between frequency and amplitude in our perception of loudness within the audible range. For example, a 10 Hz sound wave is inaudible no matter the amplitude of the wave. A 1000 Hz sound wave, on the other hand, would vary dramatically in terms of perceived loudness as the amplitude of the wave increased.

Of course, different musical instruments can play the same musical note at the same level of loudness, yet they still sound quite different. This is known as the timbre of a sound. Timbre refers to a sound’s purity, and it is affected by the complex interplay of frequency, amplitude, and timing of sound waves.


Both light and sound can be described in terms of wave forms with physical characteristics like amplitude, wavelength, and timbre. Wavelength and frequency are inversely related so that longer waves have lower frequencies, and shorter waves have higher frequencies. In the visual system, a light wave’s wavelength is generally associated with color, and its amplitude is associated with brightness. In the auditory system, a sound’s frequency is associated with pitch, and its amplitude is associated with loudness.

Personal application question

If you grew up with a family pet, then you have surely noticed that they often seem to hear things that you don’t hear. Now that you’ve read this section, you probably have some insight as to why this may be. How would you explain this to a friend who never had the opportunity to take a class like this?

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Questions & Answers

In thinking about the case of Candace described earlier, do you think that Candace benefitted or suffered as a result of consistently being passed on to the next grade?
Herlande Reply
Lees: how many types or branches of psychology do we have?
Samuel Reply
roughly 10
wow! that's cool
it ranges from occupational psychology to forensic psychology
alright dear thanks a lot
how is gratification learned ?
Mike Reply
when a feeling or desire is satisfied
By studying psychology would this help me help others as well as work hand in hand with my studies on human resources...?
Brenda Reply
Learning more about the mind and how it works it's functions...mental disorders or illnesses, also how to help others dealing with crisis....so many ? right now I'm new to all of this and it would be great to get all the 411 on psych 101...anything and everything is appreciated.
Why does someone want to study psychology so much?
Mary Reply
I want to study psychology because I want to help people, investigate the science and create the sphere of people who will be experts in this domain...
there are so many reasons.... personally I love doing so because it helps me learn more about myself, my friends & family, helps me better understand why others act like they do & also aids in relating better w others.
The same reason why anyone would do anything really. It's either to help people, find solutions, the curiosity of people (me) and just another motivation throughout life. It depends on the person. Psychology is one thing, but like every other subject, there's branches. A person can learn about
research to connect sample to the population (stats), how the body of people and animals work, how people learn, what drives people to do what they want. It all comes down to the person what they're so passionate about. I'm criticized by my own mother about psychology being a difficult major because
she took a class, but I'm learning towards the social psychology, of course I have many other hobbies that include drawing, writing, even learning languages to the best of my ability (Japanese, Italian, French).
This is certainly a very good question, but I'm being too quick to judge and speaking about everyone. Everyone might have a different say, but we are all similar.
tu parles francais Sebastian?😁😄😄tu as quelle niveau, et est-ce que tu penses que tu parles tres bien francais?😁😃
Someone told me that some people who are taking this course, has past that is mentally and emotionally painful... and those experiences triggered the person to choose psychology as a course.
I thought about it, and realized one thing about myself. So I'm asking about this, and want to know your (others') opinion.
I read the mind of the people to solve their problem and motivate them for good deeds then there are many reasons to learn performing to explore then
To be honest, I suffered from many traumas in my life, but even from an early age I always wondered why people act a certain way or do certain actions e.g. "Why do evil people become evil?" stuff like that and from then I was interested in psychology but without knowing it was actually psychology ^^
Maybe these traumas was a motivation for me to study more about it or maybe they were life changing experiences that if I experience them I could help more people because I always thought that I have to help people from an early age~
agree with @maryjoy. because psychology is the study of behavior patterns. It helps to attain the understanding of people's behavior.
@nikolaMadas I said I was learning, no i cannot speak French. I do not think I speak French well. How I can understand reading this, I am fluent Spanish and it's similarities (Mexican-American). I don't know if I suffered, but I've certainly been curious about people and animals alike.
not just behavior patterns, the mental process as well.
@sebastian yeah. thanks for adding.
I personally have strong interest and passion for studying and understanding mental health problems and how to solve these problems. That is what motivates me the most
exactly. why would we want to study psychology. the answer is in the question
psychological aspects and behavior help us better understand each other.
psychology to me,has this superpower feel to it...being able to modify,improve and predict certain mental processes and patterns...is amazing...
It helps you to know who you really are.
I study psychology to know more about myself. My behaviors both conscious and subconscious. It has helped me so much.
when u think you got it all figured out there's another day and another part of yourself you discover. another part of the world around you to explore and absorb
I study to be as understanding as can be.
I'm 16 and I want to become a general psychologist one day so I take every chance I can get to learn as much as I can.
hey Emily, I would really recommend you watching Jordan Peterson videos. just type anything like Jordan Peterson on meaning of life. Trust me it'll help you reach your aim a lot quicker than otherwise
Happy to help
denial I need to know more about it
I would like to learn how the mind works and more on mental illness ....!
watch Jordan Peterson vidoes on YouTube. I'm telling you, you'll learn a lot!
Thanks @Habib, I will..
I think everyone who starts a career or study in psychology and psychiatry can come from any background, pain related or not. I myself stick towards the main reason which is learning about the pain I have experienced in my childhood. Pain does not define us, how we react to the pain does.
I am earning Psychiatric doctors in Feature which course I can do
Rais Reply
nowadays i just want to be alone cause i feel that everyone hurt by me and i don't want this but i don't know why its happening to me .....all people just starting disliking me.... I'm not bad...
Reema Reply
why do you feel they start disliking you?
i don't know
im broken this time
Is it their behavior or do they say specific things that make you feel this way?
you are doing something wrong, never disagree with their opinions no matter how bad they are, you'll feel the change or if the situation is really bad then the world is big enough dear you'll find better people just work on yourself in context of career
and the criticism...
if people criticize everytime they realize us that I'm a bad person disgusting person... so what should i do
i know myself I'm not that kind of a person i just want to spread happiness all over
once you achieve success everyone will be under your umbrella not because they are kind but because of their self motives thats how the world runs, dont you feel down
i try to fo my best but I don't know i have a feeling that i can't do anything
dont get into that mess! ignore these people who tend to feel you small, focus on yourself try to find better people bu indulging in different events nd all that too related to your profession
hmm i must do it
that feeling is given by them its not you, you are way more than you think
thank you so much for encouraging me im feeling better now thank you so much
okay tc
thank you
good night
it's a battle which we all have to fight. it's the part of journey. Learn something, give it sometime, give yourself permission to fail and you'll see how everyone around you will start to notice you
if your religious you can change mindset to (take years it's no over night fix)everything that happen on your time line I already predestined. God then tests his strongest soilders take care, get fresh air xxx Slams Rahma
start a new day with a new energy and felling ..
if a person don't feel hunger due to vegas nerve and is emotional almost neutral an rarely show any kind of emotion then will he be considered consious
arjit Reply
how come an team captain won't fit the prototype for the concept of leadership on an athletic team?
Yoshida Reply
A leader can't be selected to lead if he hasn't being tested.
what are two kinds of behaviour explain with the the help of example
Karan Reply
overt and covert behaviours
what to do? when it seems no possibilty anywhere? i was given the golden chance to make mylife but i ruined it. now i don't know what to do next, i have broken the trust of my parents. will they ever give me another chance ?
Anjli Reply
Anjli.. u are facing the same problem too? ☹️
yes sometimes i also feel depressed, and want to harm myself for i have done to myself
I believe everyone at some point in their lives missed opportunities or lost something that would make their life so much easier, But let me tell you that this just makes a person even stronger. It's never too late to get back up on your feet and start again. It might not be now, but when you feel--
--like it, I'm sure you'll do great things and your family might even deeply appreciate that gesture ^^
will my family give me another chance ? would they trust me again ?
let me give u a hug anjli. thanks for comforting words anonymous user. :) but to start over. the big question for me. how? and i often cant sleep because of that
Of course! Your family will be happy if they see YOU doing better. My family gets disappointed with me when I don't treat myself better but then I realised later on that they were secretly worried about me. Don't be put down and start your self-journey in life and you'll be better and your family--
--as well ^^
i cant answer that anjli. but if they understand what u are going through and they care for u. im sure they will put aside anything just for your mental health and wellbeing. i am struggling too. hand in hand sister/brother?
you are so positive anonymous user. i hope i am as happy as u are.
The point is no matter how your schedules are, you can make time for yourself, it is when you fail to fulfil a certain goal that you start to feel worthless. Depression is also as a result of not having enough sleep time.
Thank you Haralita, and I'm always there to help if you need <3
i need to hug u back haralita
Thankyou for encouraging me anonymous user, i will do my best.
No problems Anjli <3
what is your goal anji
sorry Anjili
we all make mistakes. some bigger than others but there's always a way out and I know you'll find yours!
everything happen for a reason, Life is about knowing how to deal and live with the consequences of our mistakes ,learn from it for a better future and ..be patient maybe the next is more beautiful. Ps ur parents are everything so do ur best..good luck
depends on the situation if you want to talk about it let me when find some suggestions
i dont know what i am but seems like im depressed. but not suicidal. so stressed lately. and always anxious. sometimes i cant sleep and hv few hours of sleep. :( i dont know who to talk to. what am i?
Haralita Reply
For what do u stress about ?
i want to delete that but too late! lol. stress about studies , work , money and toxic family as well.
I feel you 100% honestly I was in horrible health conditions due to stress and work, but always know that when you feel that way it's time to take a break for yourself and relax yourself completely take a day out or if you feel tired talk to a friend or a family member, a great stress reliever too<3
are you schooling?
what if i prefer to be alone? i realised i have been ghosting a lot of people lately. idk. i just dont want any company. afraid of being judged not being good enough & to top it living with someone who constantly reminds u that u are going to fail. / compares u to others. so i just want to be alone
in university mary.
It's completely alright Haralita, some people prefer to be alone and some people are okay with that. If you feel like not talking to somebody for days or even months it's okay. Always do what makes you feel better. Also, we are humans, it's okay to fail and it's okay to have our bad days, but remem-
--ber that we as humans fail but it's okay and it's okay to find people better than you, just don't compare yourself and relax and who knows, you might become even better than them. Always prioritise yourself first and let all the negative people away, even if it's your own family members<3
<3 thanks i'll try. :)
How is social psychology relevant to the society?
onoja Reply
psychology is important in two words "Mental health".
It helps us to understand the social factors that affect our development, the way we act and our personalities as human beings and how we as humans affect the society around us.
my husband seems so distant to my feelings, calls mr horrid names, blames me for everything and so on. I dont know what to do anymore because it always seems to never be enough
Krystle Reply
im so sorry to hear that u have to face that. i dont know how to comfort u but judging by what u said. he seems toxic. and i lived with toxic people. i want to say run. get away from him. because that is what i really want to do now. but thats just me.
Just as Haralita said, you should look out for your husband. He appears to be manipulative and abusive. Don't hesitate reaching out to someone and get help & support from those who care. Toxic/abusive partners could lead to homewreck if you stay with him, Im not saying to divorce but be careful<3
let him know he is hurting you.men are strange creatures... if they know they are in control which happens to be most of the times they tend to dominate and continue the things they do even more. so if need be raise your voice and let him know for sure you guys are in this togethe n not one sided.
and then if it doesn't work out better do what the ladies said above
He may need his own help. He may not want help. Regardless, don't allow him to leech off of you and make you feel less than. Our mental health is very important and it is our responsibility. You're the only one in control of you.
find a way to determine the root cause of the issues that made him distant from you and work towards resolving them. it could be some attitudes that puts him off which you have to modify.
Just believe in God and yourself every thing will be settle on matter what the situation is believed in God. God is going to change something for you within some short days So my sister believe in the lord and keep your husband well, as guarding your own eyes
thank you so much .. me and my kids are blessed
Can anyone tell me why people think of an idea that they don't really wanna think nor do because it is evil and scary but, it simply came into thier minds.
Mary Reply
An intrusive thought is an unwelcome involuntary thought, image, or unpleasant idea that may become an obsession, is upsetting or distressing, and can feel difficult to manage or eliminate
That is from Google. everybody experiences involuntary thoughts. people certain disorders may be more.prone to experiencing them
To you? or just in general?.. Cause people have social anxiety and because you're pretty
It happens to me. And it is scary. What might be the reasons?
Do you think I need to see a psychologist?
I feel that even if bad or evil or scary thoughts come into your mind that doesn't define who you are. But it does mean that you are human don't worry too much about it
If you think a visit to a psychologist is warranted then go for it. They will make the determination if their services are necessary. Don't diagnose yourself of anything and keep an open mind
Mary I think everyone thinks of evil and scary things just everyone don't act on them.
What you don't like that will come your mind always
its normal.every human being think bad things in their life but ultimately its their good and positive outlook which curbs or hide their negative side..try to do meditation and keep positive thinking
That's the Id part. it's fine as far as your super ego is overpowering.
sometimes demons will try to put thoughts in ur head that didn't come from you, to make you think something is wrong, but the only way to fight back is to ask Jesus in ur heart and believe in Him and the demons have to leave
what is a true experiment?
hello, I am Solomon
hi solomon
Actually It is normal for us to have intrusive thoughts once in a while, but the reaction to how we cope with the intrusive thoughts and the occurrence of it determines whether or not you should go visit a psychologist. For example a perfectionist or an OCD person may suffer from it
Yeah, our minds are open to all kinds of thoughts, and they are more or less involuntary, thoughts are triggered by what your mind percieves in your surrounding
Intrusive thoughts could range from family related to even your own sexuality and actions that you know you most certainly wouldn't do in real life. It's actually because we wouldn't think about doing these certain actions that our minds throws that thought to us in unpredictable times.
You think evilly when you see something close to that.
the average person wouldn't normally obsess over that action and just dismiss it as a random thought, however in cases like OCD which hence the name Obsessive compulsive disorder, don't know how to cope with these intrusive thoughts so they do compulsive actions or 'rituals' to cope with them as---
---they think it is completely wrong for them to have these thoughts (e.g. because their family might punish them for it) Therefore they do so. If you feel like you meet that criteria you should probably see a psychologist. If not and or if it's normal and not oftenly recurring, then its alright--
However it is better to be educators more about that matter and if you're still unsure then it's always best to see a psychologist or a professional.
And it is also exactly as Solomon said^^
It happens many times. Like, i was holding a knife then suddenly a thought of me stabbing my friend (who was with me at that time)came into mind. I never wanted to do that. One time I was carrying a baby while looking at the window and a thought came to my mind like she's falling from that window.
It is just scary that it happens often to me... I am worried that I might end hurting someone.. Well, thanks for the info's 😊
Nooo, everything is fine Mary Joy!!!😁😃
I think so too. 👌 I think i just worrying too much..
If it's in that case then it's alright, no worries. And you're welcome✌✌
welcome** <3
Mary, I think staying away from every situation that pollutes your mind is the best. It might be something or someone.
Hi Mary...those are some really terrifying thoughts aren't they? I'm wondering if you have suffered any severe trauma at any time in your life especially during childhood. While we as human beings may think or even say out loud that I'm going to kill that man of mine if he doesn't fix whatever or
threaten a loved one with bodily harm in a joking manner and at times during periods of high stress such as a divorce while fighting for custody we might even think some alarming thoughts about harming our ex-spouse those thoughts are quite different from the scenarios that you are describing.
Yours seem to be random and not attached to any sort of anger or anxiety toward the people that you are wanting to do great harm to yet your thoughts are wanting to stab a friend with a knife and cause great harm to an infant. I think that for your peace of mind it would be a positive thing to seek
some counselling and examine why you're having these thoughts and what could be the reason for having them. I applaud your courage and your honesty and I'm getting the feeling that when these thoughts happen thy can be somewhat intense in the moment and that's a frightening situation for anyone!
There may be several reasons as to why you're having these thoughts...and it sounds as though they're not 2-3 second fleeting out of left field what the hell was that type of scenes, but a scene that plays out like a plan of action and that is what's scaring you. I may be totally wrong if so please
can be OCD, not everyone understands the different types. I experience growing up called Harm-OCD, Google it. these individuals don't want to do harm, but have thoughts, images or urges that come in and sometimes have compulsions or rituals such as checking, asking for reassurance, etc.
please forgive me for possibly putting words in your mouth. That is not my intention, but if you're having these types of thoughts often, and they're as I described them, then something is amiss and seeking some professional guidance would definitely help you to find the answers that you seek.
I wish you all the best my dear and do take care of yourself. I've always been the type of person to want to get to the bottom of things and get to the truth. That's the only way I can have peace of mind; by getting answers from the most reliable sources then do what's needed to move on!
I remember I replied to this messages before but I just don't know why it wasn't here already.. 😄 Well, there is this question I asked but I can't remember what...
I believe it's a part of id. That idea is there, maybe due to ones feelings, or maybe due to the interaction of ego and id.
Intrusive thoughts. If you have this often, is it one effect of childhood bad experiences (like childhood molestation)?

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