# Questions tagged [wave]

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### Need help with detecting onset of audio in wav file

I'm new to DSP and I'm learning as I go. I have an audio file with a chirp signal(2kHz). I played and recorded this chirp signal and the recording has a lot of environmental sounds. Here is my code:
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### Why do waveforms that are symmetrical above and below their horizontal centerlines contain no even-numbered harmonics?

All About Circuits site states that waveforms that are symmetrical above and below their horizontal centerlines contain no even-numbered harmonics. Can somebody explain this mathematically, or point ...
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60 views

### are Ultra sound signal amplitude dangerous? [closed]

First sorry if this question if it's out of topic but I'm very intrigued The human ear can hear a specific range of sound waves frequency. and huge amplitude of those sounds can damage the ears but ...
143 views

### difficulty in understanding amplitude, frequency and period

I have difficulty in understanding of some fundamental terms as amplitude. Can be there more than one amplitude for a signal? The following expression is combination of 3 sinusoidal signal, so are ...
277 views

### Is it possible to encrypt an audio wave? NFL Example

In the NFL, quarterbacks receive playcalls from coaches over their helmet's wireless interface. Someone mentioned how occasionally, these radios will pick up interference from airplanes, and that ...
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### frequencies in sound: multiple possibilities?

First, I am by no mean a sound engineer (as you will guess later). I was just wondering something while looking at the waveform of a .wav for a given shape of waveform on a duration of 2 sec for ...
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### Extracting metadata from wav files [closed]

I was curious if there is a way to extract metadata from wav files. For instance, can you get bpm, key, instrument, etc. from a .wav file on upload?
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### How to Extract a Period of a Periodic Pulsed Signal?

I rercorded a sequence of zeros and ones which is repeated many times. However, the first and the last repetitions may not be complete because I have to start recording at a random time, so the ...
387 views

### Windows Audio WAVEFORMAT buffer BYTE to 16-bit int

I am trying to understand audio-buffer processing at the low-level for the first time. I have the following C++ code copying WAVE-format byte data from capture buffer of Window Core Audio (*ppData in ...
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### How to compare two audio files that maybe have been recorded in the same environment

I have two audio files that I think they were recorded in the same room. Is there any tool that can be used to compare both of them. Knowing that sample rate and format are the same. Thanks
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396 views

### Equation for impulse train

I am looking for a formula (Fourier series) to generate an impulse train waveform - a spike-wave with amplitude and period both $1$ – so that $f(x)$ has value $1$ at $x = 1,2,3,4...$ and $f(x)$ has ...
15k views

### Mathematical equation for the sound wave that a piano makes

Is there a mathematical function that can output the sound that a piano makes at different frequencies? So if the simplest equation for a sound wave (at a given frequency and for a given sample rate) ...
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### Pitch fluctuates unexpectedly in simple sine function

I wrote a very basic C program to play a sine of a user-specified frequency. In the interest of portability, I have it spit values directly to stdout, so hopefully you can reproduce my problem on your ...
1 vote
172 views

### When simulating a voltage divider using wave digital filters I get inversed polarity outputs

I'm studying wave digital filters for my bachelor's thesis and I'm finding problems in implementing a voltage divider to test my knowledge. Here's the circuit that I'm trying to simulate and the WDF ...
1 vote
353 views

### wavwrite with 32 bits per sample seems to overflow?

I am trying to generate a 32bit PCM wav file with octave, the file shall contain a single full-scale sample (0db impulse). I am getting the expected result when using 24 bits per sample: ...
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1 vote
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### Is there a special case in which wave atoms convert to curvelets?

I'm new to multi scale transformations. I was wondering if there is a special case where wave atom converts to curvelet transform? Can I use wave atom parameters to have curvelet properties?
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### How to triangulate 2 sources on a 2d plane formed by 4 sensors?

I have 4 sensors capturing signal data. Signal distribution speed is constant and known. I have sensors positions in 3d space. Also, I have an amplitude/frequency decomposition for data received by ...
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### How to "draw" the function/wave to send symbols using QAM?

Say you have the following 8QAM constellation diagram: Say, you want to send the sequence: 001 110 101 000 001 How would you draw the function/wave containing the symbols? My problem in ...
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### In DSP - is it true that the only type of interfering wave occurs when frequencies match? [closed]

Therefore, any other frequency, no matter the amplitude, won't interfere or degrade original wave in the DSP frequency domain systems?
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744 views

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### Combining 2 sinusoids of equal amplitude with different frequencies into 1 new "wave"

This question is about combining 2 sinusoids with frequencies $\omega_1$ and $\omega_2$ into 1 "wave shape", where the frequency linearly changes from $\omega_1$ to $\omega_2$, and where the wave ...
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798 views

### How do I sum the discrete cosine transform cosine waves?

Sorry if this sounds like a stupid question, I'm new to DCT. I've implemented various types of DCT (like IV and II) and they all give vastly different coefficients. From what I've read, the DCT ...
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826 views

### How audio watermarks are captured

I have read that we can use audio watermarks to "identify the original produces of the material or the consumers of the media." How consumers of the media is measured by audio watermarks? Lets say ...
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437 views

### Why LFO should be alias-free?

I'm really tripping about this point! I try to reason with you and explain what's my trouble. Consider a scenario with Sample Rate 44100hz and a LFO square wave that will modulate some internal ...
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2k views

### Generate loopable sine wave cycle for given frequencies

I am somewhat new to DSP so bare with me. I am working on a simple wavetable oscillator. What I am trying to do is generate one cycle of a wave form for each note (frequency) and store it in an array ...
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1 vote
295 views

### How to mix two audio files recorded with different settings to obtain a realistic result

I am a software engineer, currently working on a signal-processing related project, which I am new to. For evaluating the algorithm(which is written in R), I need to mix (merge) two different audio ...
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1 vote
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### Moving Average of sinusoid

If you calculate a simple moving average over a window length that is equal to the period of the sinusoid, you get a straight line (=0 because the wave is symmetric around the X-axis): the wave has a ...
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1 vote
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### If you had supersonic hearing, would you be able to hear the carrier wave of an AM radio station?

Would you be able to hear the carrier wave of an amplitude modulated station, if you could hear in the MHz range, or would the high frequency be filtered out after rectification?
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### Can you turn a square wave into a sine wave using a low pass filter?

And if it could, would it make the sound of the square wave thinner than before because of losing its harmonics?
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### 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 ...
153 views

### Computing of speech signals modulation entropy

I got a question regarding to modulation entropy of audio signal. There is some literature I found about this topic, http://www.irit.fr/recherches/SAMOVA/FeaturesExtraction.html#me. I've read sample ...
144 views

I need to play thousands of simple sounds (generated tones) at the same time. If I am understand correctly there should be a way to add them together in complex wave but i really can't see the light ...
1k views

### How do you construct common waveforms (square, sawtooth, triangle, noise) from sine wave partials using an IFFT?

In the lovely image below we see the addition of sine waves making a square wave. I am coding a wave table synthesiser and thought it would be great to get the user to be able to fiddle with the ...
1 vote
1k views

### Python: write .wav to chosen directory [closed]

I can only write .wav files to the current directory fname = 'bassswoon.wav' wav = wave.open(fname,'w') wav.writeframes(struct.pack('h', bassswoon)) wav.close() ...
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1 vote
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### How to perform sine generation (in C)?

I am interested in how should a listing for a program look like that will generate a sine of f=50hz, using the next arguments for any moment in time. ...
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### Generating a noisy sine wave in Python, efficiently

(Questions after code block.) For now, I am generating the sinusoid and the noise separately and then normalising the amplitude so I can write the signal to a .wav file (16-bit, 16kHz). ...
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637 views

### Why every musical instrument sounds different than any other while listening?

This is soft question.I am not expert in music. We know that English language has 26 letters (which are again grouped into vowels and consonants) , while language of music is same all over the world ...
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### Formatting issue WAV - MP3?

I have two "sources" of audio: record WAV audio files (44.1kHz, 16bit, stereo) with Linux arecord and convert them with LameMP3Encoder to MP3 files (44.1kHz, 320kbps, 32bit**, CBR)*** record MP3 ...
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### What is the Sound of a Solution to the Wave Equation?

What is the sound of a solution $y(x,t)$ to the Wave Equation $\frac{\partial^2y}{\partial t^2}=c^2\,\frac{\partial^2y}{\partial x^2}\enspace$? To be clear, I don't look for a solution of the Wave ...
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4k views

### Removing unwanted square-wave noise from a signal

I have a signal, s, given at the end of this message. I need to remove the square wave shape from it. The desired signal is actually very small and it has been contaminated by a strong square-shape ...
1 vote
2k views

### FFT calculation suitable, Wav File, Java

If I have a wav file with this characteristics: 16bits (2 Bytes per Sample) 32000 Sampling Rate 60 Seconds 2 Channels then I have: ...
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1 vote
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### Unsupervised learning algorithms to detect anomaly in waves

I have a sample of graphs (more than 10000...). that look like in the image below: I am searching for an unsupervised learning algorithms that can help me to detect anomalous observations. Here what ...
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1 vote
4k views

### Downsampling PCM Audio

I'm looking everywhere for solutions for audio downsampling. However for one reason or another they are incomplete, sometimes buggy, and sometimes are in a programming language I cannot understand. ...
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### Convert Triangle Wave to Sine Wave

I have this triangle wave as input: and I want to derive a sine wave out of it. How do I go about it? PS: I am doing this in Lua, so any piece of code close to that language would be appreciated.
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### Given two waves, 441 Hz and 700 Hz, how many samples long is each wave's period if the sample-rate is 48 kHz?

The title says it all. I have two waves, Master and Slave. Master is at 441 Hz and Slave at 700 Hz. The sample-rate is 48 kHz. I want to know how to calculate the period of each wave in terms of ...
1 vote
220 views

### generating a waveform in matlab for rohde and schwarz signal generator

We are doing a test which consists in sending a waveform from Matlab to the signal generator SMB100A and sending it through a cable to the r&s spectrum analyzer just to have a channel. We set the ...
1 vote
2k views

### Does Wav format supports writing complex values

I have a sine tone, doing some math, and finally gets an harmonically accumulated sine tone in complex numbers. I do want to preserve the phase information of imaginary part on the other end, which ...
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1 vote
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### Wav file scale factor

I seek a scaled audio file format for my dsp output. I'd like to produce "scaled wav files", when I've done my pre processing. Eg. if the amplitude is 15.5 (of whatever unit), you should be able to ...
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