Questions tagged [sound]

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4 votes
2 answers
6k views

Audio time stretching, without pitch shifting

This might be a Sound Design question, or a StackOverflow question since I am attempting to do this with Java. I would like to play back a sound at the same pitch, but stretched out in time. My ...
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2 votes
1 answer
873 views

Finding the right measure to compare sound signals in the frequency domain

I am comparing the spectral contents of some sound signals with MATLAB. I have quite a few measures but wanted one that represents the centre of gravity of the spectrum. I used ...
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5 votes
3 answers
11k views

Is there any free software that can recognize and classify sounds?

i am making a smart home automation software and i would like to know if there is any software that can recognize noises such as speech ,playing music,phone ringing etc The exact software i am looking ...
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1 vote
1 answer
588 views

Resonant peak frequencies for phaser effect

I have a conventional phaser setup with allpass filters and feedback. I can calculate the peaks frequencies of the phaser when the allpass delays are set to 1 (then they work as simple one sample ...
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0 votes
1 answer
956 views

Determine Sound Intensity in SPL

I am recording ultrasonic sound using "Earthworks M50 50kHz Measurement Mic" and the sound card is "Rolando Quad-Capture USB 2.0 Audio Interface". The recording was done using Matlab into a wav file. ...
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0 votes
1 answer
162 views

Male and female voice spectrum

I have a set of data which consists of male and female voices. They are pronunciation of a same sentence. What's the appropriate method for getting an average spectrum for the male and female voices ...
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  • 701
14 votes
4 answers
24k views

How to compute dBFS?

I asked myself how to compute dBFS (dB full scale) from a value of sample between 1 and -1? and in general?
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7 votes
1 answer
24k views

Why should one use windowing functions for FFT?

So I just revised my pitch calculation algorithm using a harmonic product spectrum algorithm. I was just curious about why this explanation of Harmonic Product Spectrum states that you need to ...
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  • 271
6 votes
3 answers
4k views

How to de-noise raw sound data

What techniques/algorithms can I use to remove noise from a raw recording of sound (voice)? The purpose is to get a smoother graph (removing the "jaggedness"). What I have tried was to average-out ...
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  • 163
8 votes
2 answers
7k views

Loudness of PCM stream

I'm receiving PCM samples through stream which is one channel, 8000 samples per second. I figured out way of finding out loudness by calculating 'force' of signal by adding abs value of every next ...
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  • 211
3 votes
5 answers
2k views

Pitch Detection: avoiding frequency doubling / halving

I am working on a tuning app. I have so far tried 3 different libraries with a number of different algorithms. However, when I compare to other tuner apps, I seem to be getting frequency doubling on ...
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  • 133
3 votes
1 answer
851 views

What features describe audio signals? (Besides frequency and amplitude)

I recorded sounds with a microphone and I try to distinguish them in my Java program. The frequency works quite good, but if I look at the fourier transforms it seems like there should be more ...
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  • 133
0 votes
1 answer
7k views

how to apply Short-time fourier transform to code in matlab

Please Help, I have a white noise signal that I created and need help to apply the Short-time fourier transform to my code so that it can do the bandpass filtering. I am trying to put it in the code ...
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0 votes
1 answer
471 views

Modelling propagation of sound wave by particle simulation

How might one model the propagation of a sound wave through a 3D environment with obstacles in it? My initial thought would be to use freely moving particles that repel one another; with sufficiently ...
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  • 1,307
3 votes
2 answers
734 views

Signals cross-correlation

I am trying to measure phase difference between two received waves which are recorded by two separate PC's (microphones). The two PC's starts recording at the same time, then I make a sine wave sound ...
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3 votes
1 answer
606 views

Why are zero values added in the FFT of a concatenated noise signal?

After concatenating an 11-second *.WAV (sample rate 44100 Hz) file 27 times (just by gluing them head-to-tail), I obtained a ~300-sec noise signal. I used MATLAB(2015b) and the FFT function on both ...
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  • 288
2 votes
1 answer
2k views

Colored noises: Stationary or non-stationary?

I know for sure that white noise is considered as a stationary sound, but is that true for the rest of them? http://en.wikipedia.org/wiki/Colors_of_noise Also, can we meet some of these sounds in ...
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1 vote
2 answers
241 views

Multiple peaks in a same signal?

I am working on peak detection in different signals, the signal plot looks like this: After applying peak detection algorithm and tuning it for each signal, final output looks like this: As you can ...
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1 vote
1 answer
144 views

Multichannel input/output evaluation board

I'm working on a project at school and the first step is to choose a dsp/evaluation board but I'm having trouble. The project is to create a system that can be used for a variety of audio applications ...
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  • 11
1 vote
2 answers
835 views

Audio interface or External sound card?

I want to create a microphone array that can be connected to my laptop. Previous discussions in stack exchange and other forums suggested me to get a USB audio interface. I would want to do a lot of ...
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0 votes
2 answers
4k views

How to transform SoundWave Picture to sound?

I would like to recreate a sound from a picture of a soundwave. But i see a lot of theorical question. And im not sure its possible.... I mean, it is possible to create a sound... But to make ...
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  • 109
0 votes
1 answer
1k views

Normalizing the magnitude of Goertzel Filter c#

I'm trying to detect some frequencies of 18Khz with sample rate of 44100 [samples/sec]. When I pass a buffer(~4500 samples) to the algorithm it returns a magnitude in a very strange range. Sometimes ...
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0 votes
2 answers
269 views

Need help cleaning noise

I have been recording sound sample from mouse vocalisations and noticed that a background noise appeared in the recording room. the noise is clearly visible in the spectrograms of the recordings as ...
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  • 43
-1 votes
2 answers
3k views

How can I calculate Reverberation Time (RT60) from the Room Impulse Response using Python?

I have the following Room Impulse Response(RIR) in wave format here. I wanted to calculate Reverberation Time (RT60) of it by plotting its Energy Decay Curve using this Python code. The RIR is ...
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  • 139