Questions tagged [spectrogram]

A spectrogram is a time-varying spectral representation (forming an image) that shows how the spectral density of a signal varies with time.

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127 views

How many things can they be done with a spectrogram?

I found some things that can be done with a spectrogram. filter frequencies by setting the bins to zero observe what frequencies make up the signal. observe the energy or amplitude of each frequency, ...
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4 views

How to use tfa.image.sparse_image_warp?

I have the log mel spectrograms of a few audio clips and I am trying to augment the spectrograms using tfa.image.sparse_image_warp so that time warping can be achieved as done in Google's SpecAugment. ...
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31 views

Window overlapping FFT

I have a sample array of 16,384, I apply FFT on every chunk of 128 samples, and I apply Hanning window on every sample with the chunk size of 128. so I am getting back a 128x128 window spectrogram. I ...
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3answers
75 views

What is really the Mel-filterbank?

After applying STFT to a signal, you typically need to convert the frequencies to the Mel scale. Typically the frequency values range from $0$ to $N/2$, where $N$ is the width of each sliding window. ...
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4answers
1k views

How to deal with audio with different length in Audio Classification

Currently, I am trying to work with the Dataset UrbanSound8K to try some Audio classification. And I got stuck in the preprocessing step already. Since the audios are of different lengths, like 4 ...
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1answer
35 views

How to get rid of noise in audio files?

Is there any method to get rid of noise in wite circles of the spectrogram? I have done the high pass filter for a cut-off frequency of 1 kHz. And I'v also done a adptive noise reduction in adbobe ...
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1answer
24 views

How to get coordinates(x(time),y(frequency),z(intensity(db))) from spectrogram?

I have created this spectrogram from a wav file. Please have a look: enter image description here I want to get the x = time, y= frequency, z=intensity(db) of every pixel of the spectrogram. How can ...
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2answers
163 views

How to get coordinates(x(time),y(frequency)) of spectral peaks from spectrogram?

I have created this spectrogram from a wav file. Please have a look: As it can be observed clearly that my somewhat spectral peaks are visible. I want to get the x = time, y= frequency of these ...
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0answers
16 views

Why is the mel filter bank used to create a mel spectrogram?

The formula for converting frequencies from Hz to mel scale is as follows: $$2595\log(1+f/700).$$ So why is the mel filter bank used? What is the origin of the mel filter bank?
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2answers
57 views

STFT with varying window lengths (like the continuous wavelet transform)

I was wondering if it is possible to use windows of varying lengths when making a spectrogram based on the short-time Fourier transform (STFT). That is, for higher frequencies I would use shorter ...
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0answers
70 views

Time-Frequency analysis of IQ data in MatLab

I am new to signals processing, and am trying to match the information I'm getting out of MatLab to that taken from a commercial spectral visualization/playback tool. That is, I know what my data ...
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1answer
54 views

Power Spectral Density Reconstruction

I am from an ML background and I am working on MP3 audio reconstruction and I have managed some amount of spectrogram reconstruction but I have noticed that the higher frequency end of the generated ...
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30 views

What is the unit of the color axis on a Matlab spectrogram, and bandpower?

I am new to signal processing, but successfully made a spectrogram with Matlab. It is nice and working, showing the expected output on the graph, but I just cannot understand what the numbers mean on ...
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1answer
41 views

generating log mel spectrogram using librosa

I have come across 2 different ways of generating log-mel spectrograms for audio files using librosa and I don't know why they differ in the final output, which one is "correct" or how ...
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1answer
86 views

Is mean squared error or absolute error on two spectrograms of two different wav files enough to compare how similar they are?

I've been working on a genetic algorithm to figure out how to play a guitar chord just by listening to it. I have it all working now, but the system I am using to compare how 'similar' a guess is to ...
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1answer
166 views

Continuous wavelet transform subsampling at lower frequencies?

I am not completely confident in my understanding of wavelet theory, but since I am currently in the process of creating a CWT scalogram tool, I have to ask: Is there a theorem allowing us to ...
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2answers
71 views

Questions about MP3 bitrate conversions

I was trying to analyse the lossy compression of MP3 audio files through their Spectrograms and the results were something like this (where the upper is 80Kbps and lower is 128Kbps). It is obvious ...
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2answers
108 views

Why does Matlab spectrogram look stripy when windowed input is zero-padded?

I am working on a little project, and stumpled upon something I cannot understand yet. I am learning cognitive science, and don't have DSP knowledge background, only learning from what I find on the ...
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2answers
1k views

Quantify the difference between two audio spectrograms

I have two speech signals of the same length. They contain the exact same speech content but are recorded from two different microphones. I want to compare the differences between them. 1) Assuming ...
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1answer
143 views

Normalizing vectors to be the same size to retain PSD data

Context: PSD=periodogram(y) in MATLAB gives the PSD (power spectral density) estimate of a sound-source signal. I want to find the local maximum within 3 different ...
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1answer
6k views

Spectrogram, time vs frequency localization, and length of signal

So I'm having some trouble conceptually and am hoping somebody can clear something up for me. This is long and I apologize for that but I want to provide as much information as possible so that the ...
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1answer
84 views

Determining statistically the bandwidth of a signal from a spectrogram

My question is how to determine the parameters of a signal from a spectrogram statistically. The most important parameters that I am looking for are the lower and higher frequencies of the signal. I ...
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1answer
952 views

Comparing band-pass filters and convolutional kernels?

I am currently working on extracting features for speech recognition purposes. I wanted to try an approach similar to MFCC features in which the center frequency of each band pass filters are placed ...
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1answer
719 views

Is the Auditory Spectrogram the same as the Magnitude Spectrogram?

This is in the context of speech signals. The magnitude spectrogram is computed by framing the signal into short time windows, applying a hamming (or similar) window, computing the fft over each ...
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1answer
720 views

High resolution spectrograms

I have a recorded audio signal that I would like to convert into spectrogram with the highest possible yield of information. The audio clips I am working with is about 30 ms long and contains ...
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1answer
192 views

How can you 'perfectly' reconstruct phase for transients in a modified audio absolute spectrogram?

I am currently working on the absolute spectrogram of an input audio signal. I am using non-negative matrix factorization to separate out the rhythmic components (bass drum, snare drum and hi-hat) of ...
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2answers
216 views

Fourier Like Spectral Analysis with Uneven Intervals and Redesigned DFT Matrix

I intended to use a discrete Fourier transform (DFT) on a time series sampled at uneven intervals. What I did was to calculate a DFT matrix where the elements are the values at the uneven locations ...
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2answers
203 views

Augmentation for EEG signal classification using Deep Learning

Augmentation is a technique that we use in deep learning for expanding the training dataset. It includes different ways of modifying an image and adding it to the training dataset. My question is if ...
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1answer
66 views

How do I interpret an image of a spectrogram of an audio wind signal?

I am running the following code in python to get the spectrogram of a audio signal of wind: ...
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0answers
41 views

Tell a recording of Martian wind from a recording of Earth's wind

Perseverance Rover's SuperCam Records Wind on Mars, sol 11 (Credit: NASA/JPL-Caltech/LANL/CNES/CNRS/ISAE-Supaero) How do I interpret an image of a spectrogram of an audio wind signal? (Credit: ...
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98 views

Welch Method FFT Python - Scaling factor?

I've been implementing a Welch method FFT and I am trying to work out the correct scaling factor that should be applied to the output of the function so the PSD is accurate because at the moment it's ...
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1answer
112 views

Math.Net and alglib returning different FFT outputs by default

I am developing an application in C# with spectrogram drawing functionality. For my fist try, I used MathNet.Numerics, and now I am continuing to develop with alglib. When I changed from one to the ...
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22 views

Audio-Processing for DeepSpeech model

I try to understand audio signal processing from Deep Speech: Scaling up end-to-end speech recognition paper. Quote: Since the Switchboard and Fisher corpora are distributed at a sample rate of 8kHz, ...
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2answers
182 views

Spectrum of FM signal?

If a carrier ($f_c$) is FM modulated by a single sine wave ($f_m$), its spectrum is composed of frequencies at $f_c + kf_m$ ($k \in \mathbb{Z}$) whose amplitudes are weighted by $J_n(\beta)$, the $k$-...
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1answer
42 views

Spectrogram without using stft

Can I use any kind of transform to make spectrogram, not just stft? Is it possible to get the spectrograms of a signal without using stft? What difference does it make if I calculate the frequency ...
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2answers
29 views

Stft of sinusoids

I have a sinusoidal signal of 10 minutes. For the first 5 minutes, the signal has a frequency of 100 Hz and for the next 5 minutes, the signal has a frequency of 200 Hz. 1 - If I look at the ...
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16 views

Stockwell S-Transform and multitapering

I want to estimate just the spectral amplitudes at different time points using S-transform given a noisy signal. Would I benefit (in terms of noise reduction) from an approach used in multi taper ...
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2answers
2k views

What is Causing a Cyclic 1kHz Noise Signal in Audio Recording?

I dug my old Behringer UCA202 out of my shed and plugged it into a computer. I did some tests and it appears to be working fine... apart from some noise signals on the line input channels. I'm not ...
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0answers
157 views

Python: How to generate log-frequency spectrogram from an audio?

I want to make a log-frequency spectrogram out of this audio. Later, I need this spectrogram for pitch sequence analysis. This is a sample sequence I want to achieve: ...
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2answers
2k views

What is the best way to represent audio visually? (x-post from UX)

Original Question: https://ux.stackexchange.com/q/23040/16006 I've only taken some basic signal analysis courses, so I might be missing some things. Purely theoretical question: What methods exist ...
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3answers
799 views

Phase information of a signal when creating a spectrogram

Sorry for the uninformed question but I need some help understanding this. I'm trying to understand what phase information is and it would be very helpful if someone could correct my understanding of ...
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0answers
14 views

Use of spectrograms in using deep learning on EEG related problems

I am currently working on a classification problem related to EEG signals. My professor asked me to convert those signals into their spectrograms and try various convolutional neural networks on them. ...
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0answers
30 views

Get Spectrogram from Filtered Power Spectrum

My objective is to get the higher resolution of spectrogram on the high-frequency area (2000 Hz - 5000 Hz) for a section of speech audio. I know that we typically apply Mel-scaled filter bank to get ...
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0answers
34 views

Confusion about spectrograms: conceptual problem

The following code generates a spectrogram as shown in the image. The matrix s which is the spectrogram is of size 129x40 for a ...
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0answers
46 views

FM modulation - recovering bits

I'm trying to complete one task: Download some FM modulated signals from page http://www.w1hkj.com/modes/index.htm. Calculate their spectrograms, i.e. short-time Fourier transform. Observe different ...
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0answers
71 views

How to determine number of filters in filter bank based on spectrogram of audio signal?

I want to do an analysis and than synthesis of audio signal, which is audio of vowel 'a', using Matlab. For this I need to use filter bank(array of band-pass filters). I have drawn four different ...
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1answer
118 views

How to find peak frequency in an audio frequency spectrum?

I have a audio file consisting of multiple frequencies, I need to find all the frequency peaks in the frequency spectrum after doing FFT. But the issue is how can I be able to set the threshold line ...
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1answer
601 views

How can I calculate the Number of bins per octave?

I am trying to calculate the Constant Q Transform for Monophonic audio using Python. The Python has the library to calculate the CQT , the default value of num_bins_per_octave is 12. How would one ...
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14 views

How to apply audio superposition in mel spectrogram domain

Very rusty physicist here. I have two audio spectrograms and I want to work out how to calculate the spectrogram of the superposition of the original waveforms (without having access to the original ...
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2answers
839 views

How can create a .wav bar based spectrogram on matlab?

How can I create a bar based spectrogram that updates as a .wav file is playing. This is commonly found in music players. Here is an example below: I am able to display a amplitude/frequency graph ...

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