# 8.1 Anatomy of a laugh track

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This module gives an analysis of the time and frequency domain characteristics of a laugh track. It is part of a larger series discussing the implementation of a real-time laugh track removal filter.

#### Introduction

A laugh track is a commonly heard part of sitcoms and other comedy shows found on television since the early 1950s. A laugh track can be defined as a prerecorded superposition of samples of people laughing mixed into a television show to "enhance" it. A single laugh track can be composed of a variety of male laughter and female laughter. Often individual, distinct laughs are added in at the end to make laugh tracks sound like the laughter of a live audience instead of simply something generated from prerecorded samples. All of this makes it very difficult to detect a laugh track based on relatively simple heuristics.

#### Frequency analysis

Looking at the Discrete Fourier Transforms of a laugh track(Fig. 1) and a two minute sample of a television show(Fig. 2), we notice some characteristics of the laugh track such as the slightly larger spike in one of the mid-range frequencies, which is difficult to detect, there is not much difference in the spectrum in the two signals. The spikes we see are also not characteristic of every laugh track, so it would be difficult to create a method of detecting laugh tracks solely by looking in the frequency domain. Factoring in variability such as the dominance of male or female voices in the individual laugh track as well as varying lengths and intensities of a laugh, the problem becomes even more difficult when attempting detection using DFTs and a bandpass filtering scheme.

#### Time analysis

It is much easier to look for a laugh track in the time domain because the envelope that is characteristic of a laugh track as can be seen in the figure below is much more prominent than the spikes that we see in the DFT of the two signals. This envelope follows the magnitude of a normal laugh track. After a joke, people abruptly start laughing and then the laughter slowly dies down. This is found to be the case in almost every single laugh track instance found in the TV shows that we looked at. Even if a laugh track is short, we can see the same envelope, just compressed more so than in the example. If a laugh track is quieter or louder, we will still be able to see the envelope, though this makes detection based on height thresholds more difficult as regular speech may look very similar to our envelope when a laugh track is shorter and quieter.

#### Conclusion

Other approaches at detecting laugh tracks were also considered, but envelope detection in the time domain proved to be the most effective manner of detecting laugh tracks. Matched filtering and looking for distinctive characteristics in the frequency domain proved to be fruitless. The envelope in the figure above is quite distinctive and relatively easy to detect, even with a fairly simple algorithm, so this approach was used in our detection and removal scheme.

anyone have book of Abdel Salam Hamdy Makhlouf book in pdf Fundamentals of Nanoparticles: Classifications, Synthesis
what happen with The nano material on The deep space.?
It could change the whole space science.
puvananathan
the characteristics of nano materials can be studied by solving which equation?
sibaram
synthesis of nano materials by chemical reaction taking place in aqueous solvents under high temperature and pressure is call?
sibaram
hydrothermal synthesis
ISHFAQ
how can chip be made from sand
is this allso about nanoscale material
Almas
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 is the latest information on a no technology how can I find it
William
currently
William
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
STM - Scanning Tunneling Microscope.
puvananathan
How we are making nano material?
Some times this process occur naturally. if not, nano engineers build nano materials. they have different physical and chemical properties.
puvananathan
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