Questions tagged [dbfs]

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6 votes
3 answers
1k views

What additional inputs are required to convert dBFS to dB SPL?

It is probably very well known that dBFS cannot be directly converted to dB SPL without knowing other information such as the technical specifications of the microphone. The questions are: What is ...
1 vote
1 answer
105 views

Signal flow for conversion of audio to Lzeq (sound pressure level time-equivalent)

I'm developing an embedded system which takes in digital audio from an ICS43432 MEMS-microphone via the I2S-bus to compute the sound pressure level over variable ...
1 vote
1 answer
426 views

What is the meaning of dbFS/LSB

A simple question that I am not able to find any solution online or in the literature I have. What does it mean when it something is written as dbFS / LSB, for example ...
• 13
0 votes
1 answer
337 views

Why is there a factor 2 in dBFS formula?

The conversion formula from a linear ratio r into dBFS units is the following: dBFS = 20 * log10(r). The value of ...
• 103
0 votes
0 answers
66 views

Filter a signal with a complex dB SPL filter

I've been tasked with filtering a sound with a filter that looks something like this. I don't have any real DSP training, so I'm not sure if my attempt at tackling this is correct. I can filter ...
0 votes
1 answer
337 views

How to compute dBFS from rms-values if the samples exceed 32bits

For a first approach on audio-sampling I'm currently working with the raspberry pi's pcm pins and MEMS-microphones, using the ALSA library. A problem arises when I want to calculate dBFS from a buffer'...
5 votes
3 answers
1k views

Precise 5th and 7th harmonics of a sampled sine wave

Does anyone know in decibels (to 1/100th of a dB) what the theoretical 3rd, 5th and 7th harmonic of a 0dB fs 24-bit (i.e. full-level; 0dB = -8,388,607 to 8,388,607) sampled sine wave without dither ...
• 101
1 vote
2 answers
2k views

What should my reference value be when converting FFT bin amplitudes to dB?

I want to transform my FFT output values into a dB scale, but I'm struggling to determine the function I should run each bin amplitude through. My understanding of the decibel scale is that a value ...
3 votes
2 answers
3k views

Measuring microphone Signal to Noise ratio (SNR) with A-weighting

Foreword: I have already read Applying A-weighting and user @endolith's A-weighting code I would like to measure the SNR of a microphone with the same method applied by the main manufacturers, that ...
• 1,267
1 vote
2 answers
14k views

Avoiding "RuntimeWarning: invalid value encountered in log10" when converting FFT data to dBFS

I've attached some code below that I'm having some issues with. Basically, I need to write a function to get the dBFS value of a signal at a specified Hz value, at a given channel in a .wav file. ...
• 11
1 vote
0 answers
1k views

calculating SNR from dbfs (using spectrograms)

I've the spectrogram of both noise and signal (both 5 seconds). Below image shows an example of the signal spectrogram: The colour of the spectrogram shows the intensity in dbfs (from 0 dbfs to -120 ...
• 11
5 votes
4 answers
56k views

FFT to spectrum in decibel

Here is a 10 seconds-long 440hz sine wave normalized at $0\textrm{ dBFS}$. When computing the STFT (with the code below) of this audio file, I noticed that ...
• 1,267
0 votes
1 answer
2k views

Power Spectrum in dBFs

I'm trying to get the spectrum of my signal in dBFS units. I'm not sure what is the refernce that I should devide by. I computed the power spectrum as follows: 1) FFT normalized to the number of ...
5 votes
1 answer
8k views

Is it only me or matlab's periodogram's function is confusing?

I am really confused with matlab's periodogram. First of all, it says in the documentation that its unit is "dB per unit frequency". What does that really mean? I just don't quite get it. Second of ...
1 vote
0 answers
716 views

Converting musicg spectrogram output to dBFS

I'm trying to convert musicg Spectrogram output to dBFS. With 16-bit signed integer PCM audio, and an FFT length of 2048, I'm trying to analyze the spectrogram for an audio file to determine things ...
• 111
12 votes
1 answer
24k views

Converting raw I/Q to dB

I am getting I/Q data from a software-defined radio. I want to do some stuff on signals in the data, but only if it exceeds a certain range. What is the general procedure to get dB (dBm, or anything)...
5 votes
2 answers
2k views

dBFS scaling and spectrum

I am trying to replicate the spetrum as given in Audacity and other commercial software... I am getting crazy with the correct scaling needed in order to have dBFS (with reference to a full scale sine ...
16 votes
4 answers
31k 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?
• 571
0 votes
2 answers
954 views

Matching an LPC Magnitude Spectrum to FFT Magnitude Spectrum

I'm trying to get an LPC magnitude spectrum to match to an FFT magnitude spectrum. Basically I want the peak height in the LPC Spectrum to match the peak height in the FFT Spectrum. Thanks to ...
• 475