# 0.13 Lab 9a - speech processing (part 1)  (Page 2/5)

 Page 2 / 5

In contrast, unvoiced speech has more of a noise-like quality. Unvoiced sounds are usually much smaller in amplitude,and oscillate much faster than voiced speech. These sounds are generally produced by turbulence,as air is forced through a constriction at some point in the vocal tract. For example, an h sound comes from a constriction at the vocal cords, and an f is generated by a constriction at the lips.

An illustrative example of voiced and unvoiced sounds contained in the word “erase” are shown in [link] . The original utterance is shown in (2.1).The voiced segment in (2.2) is a time magnification of the “a” portion of the word.Notice the highly periodic nature of this segment. The fundamental period of this waveform, which is about 8.5 ms here,is called the pitch period . The unvoiced segment in (2.3) comes from the “s” soundat the end of the word. This waveform is much more noise-like than the voicedsegment, and is much smaller in magnitude.

## Classification of voiced/unvoiced speech

Download the file start.au for the following sections. Click here for help on how to load and play audio signals .

For many speech processing algorithms, a very important step is to determine the type of sound that is being uttered in a given timeframe. In this section, we will introduce two simple methods for discriminatingbetween voiced and unvoiced speech.

Download the file start.au , and use the auread() function to load it into the Matlab workspace.

Do the following:

• Plot (not stem) the speech signal. Identify two segments of the signal: one segment that is voicedand a second segment that is unvoiced (the zoom xon command is useful for this).Circle the regions of the plot corresponding to these two segments and label them as voiced or unvoiced.
• Save 300 samples from the voiced segment of the speech into a Matlab vector called VoicedSig .
• Save 300 samples from the unvoiced segment of the speech into a Matlab vector called UnvoicedSig .
• Use the subplot() command to plot the two signals, VoicedSig and UnvoicedSig on a single figure.
Hand in your labeled plots. Explain how you selected your voiced and unvoiced regions.

Estimate the pitch period for the voiced segment. Keep in mind that these speech signals are sampled at 8 KHz, which means that the time betweensamples is 0.125 milliseconds (ms). Typical values for the pitch period are 8 ms for male speakers,and 4 ms for female speakers. Based on this, would you predict that the speaker is male, or female?

One way to categorize speech segments is to compute the average energy, or power.Recall this is defined by the following:

$P=\frac{1}{L}\sum _{n=1}^{L}{x}^{2}\left(n\right)$

where $L$ is the length of the frame $x\left(n\right)$ . Use [link] to compute the average energy of the voiced and unvoiced segments that you plotted above.For which segment is the average energy greater?

Another method for discriminating between voiced and unvoiced segments is to determine the rate at which the waveformoscillates by counting number of zero-crossings that occur within a frame (the number of times the signal changes sign).Write a function zero_cross that will compute the number of zero-crossings that occur within a vector, and apply this to the two vectors VoicedSig and UnvoicedSig . Which segment has more zero-crossings?

#### Questions & Answers

are nano particles real
yeah
Joseph
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
no can't
Lohitha
where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
has a lot of application modern world
Kamaluddeen
yes
narayan
what is variations in raman spectra for nanomaterials
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
how did you get the value of 2000N.What calculations are needed to arrive at it
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!