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In addition to being one of the easiest ways to populate the array, this is also a way to produce a sound that is very close to being a pure tone . By pure tone, I mean a sound that results from something vibrating at a single frequencysuch as Middle-C ((261.63 Hz) .
If you have taken a math course in trigonometry, you probably know the shape produced by graphing the output from either the sin function or the cos function. If not, it would be good if you can ask a sighted friend to Google for "sinusoidal function image", download and print oneor more of the images and emboss them for you using whatever embossing method you prefer. This will provide you with a tactile representation of a sinusoid.
In any event, I am going to provide you with a sound file named SinusoidalAudioGraph that provides an audio representation of the graph of a sinusoid.
This audio file contains an 8-second melody consisting of 32 uniformly spaced pulses at different frequencies. The frequencies (pitches) of the pulses are centered on middle-C (261.63 Hz) . The frequency deviation from middle-C versus time is based on a sinusoidal function with a frequency of 0.5 Hz.
Each pulse represents one point on a graph of thesinusoid. Pulses with frequencies at or above middle-C are delivered to the left speaker. Pulses with frequencies belowmiddle-C are delivered to the right speaker.
The audio output can be thought of as an audio representation of a graph of a sinusoid. Pulses with frequencies abovemiddle-C represent points on the positive lobe of the sinusoid. Increasing pitch represents increasing amplitude on the graph of the sinusoid.
Pulses with frequencies below middle-C can be thought of as representing points on thenegative lobe of the sinusoid. In this case, decreasing pitch represents points on the sinusoid that are further from the horizontal axis in the negativedirection.
Pulses with a frequency of middle-C can be thought of as representing points on the horizontal axis with a value of zero.
Four complete cycles of the 0.5 Hz sinusoid are represented by the 32 pulses in the 8-second melody.
Hopefully, by listening to this audio file, you can get an idea of the shape of a sinusoid.
In addition to providing the audio file to help you discern the shape of a sinusoid, I am also providing it as an example of the type of audio files thatyou will be able to create once you understand the programs in upcoming modules.
This section contains a variety of miscellaneous information.
Financial : Although the OpenStax CNX site makes it possible for you to download a PDF file for the collection thatcontains this module at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, youshould be aware that some of the HTML elements in this module may not translate well into PDF.
You also need to know that Prof. Baldwin receives no financial compensation from OpenStax CNX even if you purchase the PDF version of the collection.
In the past, unknown individuals have copied Prof. Baldwin's modules from cnx.org, converted them to Kindle books, and placedthem for sale on Amazon.com showing Prof. Baldwin as the author. Prof. Baldwin neither receives compensation for those sales nordoes he know who does receive compensation. If you purchase such a book, please be aware that it is a copy of a collection thatis freely available on OpenStax CNX and that it was made and published without the prior knowledge of Prof.Baldwin.
Affiliation : Prof. Baldwin is a professor of Computer Information Technology at Austin Community College inAustin, TX.
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