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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speech to text by phoneme extraction and then combining them

trying to write code in matlab for the conerversion of speech to text.In this I want to use spectrogram so as to separate the phonemes but not able to understand how to work with spectrogram. Googled ...
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22 views

Can uneven sampled points generate valid PSD and spectrogram?

My recording device samples signal at 100 Hz. At each sampling point, it generates 512 values (I assume due to non-ideal impulse in practice, so each impulse is actually a window with certain width ...
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3answers
63 views

Rendering a spectrogram of audio data - resulting magnitudes are all too close together

I'm working on creating an application which will render a spectrogram of the audio in an MP3 file. I'm having some trouble, though - after running the audio samples through my program, the resulting ...
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0answers
39 views

Looking for an algorithm that computes weighted average of frequencies intensity from narrow band in spectrograph

I am searching for the algorithm that takes (audio) signal as an input and outputs weighted intensity of the frequencies of some narrow band (axis X) in time (axis Y). Frequency in the middle of that ...
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1answer
36 views

Frequency resolution

I have made a stft_func in MATLAB which takes window length i.e t_short as a parameter for window length. Now, this function is ...
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1answer
34 views

Given a spectrogram, how do I calculate loudness over time?

I want to calculate the loudness of a given sound over time (like, in a graph) from its spectrogram. Can I do this from the spectrogram or is it better to do from the raw sound?
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1answer
63 views

Improve spectrogram appearance using windowing functions MATLAB

I have a program which plots data obtained in a NI USB DAQ realtime to a spectrogram plot using the surf function. I'd like to improve the appearance of the plot using some sort of windowing function. ...
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42 views

Understanding PCA

OK, I have tried to ask the same question in the math site on stack exchange but no real joy. Apologises I'd this is the wrong forum. I am trying to compute the PCA of a spectrogram.. It is 486x128 ...
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1answer
59 views

Detecting a curve with certain characteristics in a spectrogram

I have a spectrogram built by breaking a signal into chunks and taking the FFT of these chunks. An example spectrogram is: In this spectrogram I am looking for a curve (aka pitch contour) that: ...
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1answer
52 views

How to obtain the Spectrogram of a signal

I am trying to use Matlab to compute the spectrogram of a signal but I can't seem to figure out how Matlab computes the spectrogram.Consider the case where I have a ...
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1answer
197 views

PSD - Is this formula correct?

Trying to understand whether or not I am calculating the PSD correctly. Below is the equation that I am using: $$ PSD_{rms}(f_{m} = m \cdot f_{res}) = \frac{PS_{rms} }{ENBW} = \frac{2 \cdot \left | ...
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2answers
150 views

Spectrogram - Am I missing something?

I have the following signal: I'm trying to compute a Spectrogram algorithm, but, don't think I'm doing it right.. I have computed the following: 1) STFT (size 256 with an overlap of 128) 2) ...
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3answers
90 views

Will the resulting spectrogram from this algorithm be 1D or 2D?

I'm implementing a spectrogram algorithm and I get the basic concepts, however, I'm struggling with something. Let's say I have a 1D vector: ...
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3answers
334 views

Why do we get ripples in the frequency spectrum of a chirp, and how do I remove it?

The ripples in the amplitude spectrum of a linear spectrum is undesirable. I desire to obtain a flat spectrum response. Hence, how can I remove these ripples? Also, which factors (like time bandwidth ...
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2answers
471 views

Get spectrogram matrix without specgram in MatLab

I have a signal in Malab, and I need a matrix, probably transposed specgram matrix without using specgram tool. Is it possible?
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2answers
573 views

interpret wavelet scalogram

My knowledge of wavelets is less than epsilon. Bear with me. If I have a signal of two well separated sinusoids (15 and 48 Hz) plus some random noise, I can clearly make out the two in a spectrogram ...
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1answer
65 views

STFT computational burden

I have a signal with length of $N$. The sampling frequency is $f_s$. Window size is $w$ The noverlap size is set to $m$. And $nfft$ is selected for frequency resolutions. I am running a STFT with ...
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1answer
675 views

How can I compute a time-frequency cross-spectrum in MATLAB?

MATLAB has a spectrogram function for the time-frequency analysis of a single signal. It also has a cpsd function for estimating the cross-frequency spectrum for two signals. However, cpsd averages ...
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1answer
88 views

I can't figure out why spectral features are “displaced” on a spectrogram

I'm trying to create a spectrogram of a complex signal 'y', but I'm running into a problem where the spectrogram that I create appears to have its spectral features "displaced" in frequency space, and ...
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3answers
319 views

strange phenomenon in spectrogram of Windowed Fourier Transform [edited] [closed]

I am trying to understand how the Windowed Fourier transform works, so I used Matlab to create an artificial signal, and plotted the Windowed Fourier transform using a gaussian window. $x(t) = ...
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1answer
221 views

Spectrogram from Complex Morlet wavelet ( recreating article result from data)

I am trying to recreate the following results: ...from the following data: Dropbox Link (FS40.dat) The time is in milliseconds (frequency is 40000 Hz) The article state that they used Complex ...
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1answer
109 views

What information is lost, if any, in normalizing Seismic/Earthquake time-frames in an STFT to equal variance?

This might be more of a statistical question, but let us assume that we take a spectrogram, or STFT, where time is on the x-axis, and frequency is on the y-axis in this matrix. What information might ...
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5answers
2k views

generating spectrograms in python with less noise

I'm trying to do something similar to Shazam (paper here) in Python. Basically the idea is to use FFT with sliding window to transform both WAV files and recorded audio to the same spectral ...
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1answer
136 views

Gammatone filter vs 2D FFT for spectograms

I am working on speech segeration and each source I am reading , spectograms are being made by filterbanks which uses gammatone filters . I can't find a proper c++ source code which would make me ...
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2answers
109 views

Estimating noise level without 'quiet' segment

I have a signal which consists of an onset and a release period. The onset, sounding like a thud, excites frequencies across the entire frequency range (0-22 kHz). It lasts for about 0.1 s. The ...
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1answer
757 views

Spectrogram of wav file

I am calculating spectrogram of a audio file of 36 second using the following code snippet: ...
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1answer
134 views

Converting mel spectrogram to Spectrogram

I have a set of songs for which I extracted the STFT (Short Time Fourier Transform) and used the magnitude spectrum $|S|$ to calculate the mel spectrogram by using a mel filterbank matrix $M$, so ...
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1answer
62 views

Phoneme Clustering

My aim is to find cluster phonemes from a wav file. I would like to go through the following steps: I am calculating spectrogram. Calculate energy of each frame. Cluster the frames using k-means ...
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3answers
2k views

Reconstruction of audio signal from Spectrogram

I have a set of songs for which I extracted the magnitude spectrogram using a Hamming Window with 50% overlap. After extracting the spectrogram, I did some dimensionality reduction using Principal ...
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1answer
583 views

Applying FFT to PCM stream

I would like to use a .WAV file and convert it into a spectogram. Any idea how to do this with Naudio? Basically the flow should be like this, I think: Convert WAV file to PCM stream Convert PCM ...
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1answer
349 views

Programming language for sound manipulation [closed]

Having had little experience in PHP, I moved to C++ in-order to create a spectrogram, I wanted to create probably the simplest/easiest one for my first project, so easy infact I don't need ...
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2answers
88 views

What is the theoretic difference in the ways to compute the spectrogram?

I have noticed that the spectrogram for a audio signal is often calculated in different ways when the result from the DFT is transformed into real numbers; some tend to compute $|k|$ or $|k|^2$ while ...
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0answers
134 views

Points of interest in a spectrogram

We have several audio tracks, all of which are different versions of the same track under one type of distortion: the speed of the track is increased by a constant factor K (hence frequences are ...
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1answer
335 views

Spectrogram Analysis

I have four .wav files and each contain bird chirps. Given an input .wav file, I need to find out which bird it is. I have some basic understanding of signal processing. I have used spectrogram to ...
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1answer
237 views

Convolving With half-Hanning

The goal is to get a 200ms decaying delay of an audio signal while preserving the sharpness of attacks to mimick human perception of sound. The paper I'm following convolves a 200ms half-Hanning ...
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1answer
95 views

Compressing A Range Of Decibel Values to One “Representative” Value

Don't have any formal dsp experience - sophomore in college. Working on constructing a 25 band bark spectrogram for psychoacoustic analysis of audio FFT data. To do this, I'm grouping all FFT ...
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2answers
173 views

Finding the frequencies given in a wav file

I have a wav file containing a series of chords, each containing 3 or 4 notes, played concurrently. I need to find the frequencies of each note in each chord, and I can use matlab to do any ...
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5answers
342 views

Vertical lines noise in spectrogram

I have started looking into DSP and made an implementation of short-time fourier transform, using kissFFT to perform the FFT. I then render a spectrogram. An example image that I have generated can ...
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1answer
549 views

why is the spectrogram from matlab different from audacity

Something related Here are the spectrogram plots: Matlab version: Audacity version: the darker parts towards the right of the figure show speech. Silence was added to the left of the figure in ...
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1answer
2k views

Please help me analyse spectrogram

I am working on noise reduction and I need to learn how to analyze spectrograms I mixed a pure speech file with violet noise in audacity and got the following spectrograms: Matlab version ...
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188 views

When should I use a frequency spectrum rather than a spectrogram representation?

It seems to me that the spectrogram representation of a finite signal gives you significantly more useful information than a frequency spectrum. As I understand it, the spectrogram breaks down the ...
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2answers
283 views

Deriving the frequency spectrum graph from the graph of a spectrogram and vice versa?

I have a signal's spectrogram and frequency spectrum (which, if i'm not mistaken, is its the signal's fourier transform) as given below: I understand that the spectrogram plots the frequency ...
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848 views

Reconstruction of Audio Signal from its Absolute Spectrogram

I have the absolute Spectrogram of an audio signals. I lost the phase data of the Spectogram because of various processing applied on the original spectrogram of the signal. I'm trying to reconstruct ...
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1answer
243 views

Using Spectrogram to check whether aliasing will occur

I was wondering if the spectrogram can be used as a MATLAB tool to check whether or not aliasing will occur when the signal is downsampled from let's say, 44.1kHz to 8kHz? And if yes, how do I go ...
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1answer
233 views

Spectrogram for created signal

I'm trying to test the specgram function located in the signal package in octave but I'm a little confused at the variables in specgram. What I would like to do is be able to get the specgram data ...
3
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1answer
521 views

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

Original Question: http://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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4answers
16k views

How do I plot the spectrogram of a wav file?

I am dabbing a little bit into signal processing on MATLAB. And I have the following question that I would like to know the answer to. What has to be done : Plot the Spectrogram of an audio file. ...
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2answers
4k views

Improving spectrogram resolution in Python?

I'm using the specgram() function in matplotlib to generate spectrograms of speech wave files in Python, but the output is ...
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1answer
2k views

Creating a spectrogram

I've been trying to work out the logic for this task, and plan to use the KissFFT source package to perform the fast fourier transform. Please let me know if this looks about right: Allocate an FFT ...
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1answer
1k views

What is the maximal frequency resolution for Matlab's STFT implementation spectrogram()?

Matlab's spectrogram() function calculates the STFT of a signal. It describes its NFFT argument as follows: ...