Sound level adjusting when capturing from USB

Win7 and Win8, Audacity 2.1.0 and 2.0.3

What is the right method to increase voice level when capturing from USB device? Old C-cassets have often to low soud level. When capturing sound and making it to mp3 format is possible to correct that with Audacity settings. In wich procedure and how? Is there maybe an automatic level correction on? How to do it manual way?

The Amplify effect will pre-scan the file and automatically default for 0dBFS peaks, which is the maximum you can go without clipping (without distorted flat-top waves).

Audacity doesn’t apply effects in real-time while recording, so do that after recording.

If these are music, that’s as far as I’d go. You can do that on a song-by-song basis, or if you want to keep the relative loudness between songs on an an album, Amplify the whole recording in one step. (They probably won’t sound as loud as modern highly dynamically-compressed MP3s).

If they are voice recordings you can also try can try the Leveller effect or the Compressor effect. (You can use compression on music too, but you reduce the dynamic contrast of the music.)

Many thanks of replay. As far I now understand the voice level will be adjusted after recorging (in this case fom USB capture device). Then the souds are in Audacity project mode. When doing it to .mp3 format set Amplify effect on. It will do the job, all musik in same project. Is that right? When it is automatic, do it make songs or music level quite equal also in diffrent pieces?

Are there some automatic level adjustemets when recoding too? Good to know.

As I said in your other topic, you also want to make sure you are recording at a high enough level in the first place, or you will hear hiss when you amplify.

Make a test recording first. Play a loud part of the tape then use the Audacity Recording Slider (microphone symbol):

to adjust the recording level so that the recording meter reaches a maximum of about - 6 dB.

No. Amplify or Normalize set the loudest peak in each track to the level you specify.

Having the peak in each piece at the same level (for example, -3 dB) does not make every piece sound equally loud, especially with music.

If you want to specify equal loudness in Audacity you either have to add the ReplayGain plugin to Audacity, or export the MP3 files as they are then adjust their volume with MP3Gain.


Now I have tested Amplify effect. My Audacity is in Finnish language. So there was not Amplify effect but I found it under “Vahvista…” what is in English about “make sound level higher” :smiley:

When open it there was this adjustements: Amplification (dB) 19,1, New Peak Amplitude (dB) 0,0 , Allow clipping No. Result was quite strong amplifying; when listening voice measuring meter reatches red 0 point. Maybe 19,1 was too much. Musik was loud but still quite good.

By default, Amplify sets the peak to 0 dB. See Audacity Manual and Amplify and Normalize.

It depends on the music whether setting a peak of 0 dB sounds too loud or not loud enough when you play the whole song. See the links in my previous post about ReplayGain.


What should to be the recommend level to Amplificationj (dB), now I have there 19,1.? Should just this be 6? What it the meaning of this adjustment? I understand that these adjustements are only used when using Amplify effect. Where set the level when Amplify effect is not in use?

I will study ReplayGain but dont know if it nessessary of all normal users.

If you change Amplification (dB) to 6 dB when Amplify opens set to 19.1, then the New Peak Amplitude will only be -13.1 dB. Is it enough? Only you can decide that.

You can use the Audacity recording volume slider to adjust the recording volume while recording.

You can use the gain slider on the Audacity track to adjust the level while you play the track. Unlike Amplify, this does not affect the waveform (does not change the level of the audio data). However when you export as an audio file, the gain you choose will be applied to the exported file.


Many thanks for your patience! Can I see somewhere how the peak amplitude changes when adjusting Amplification (dB) slider? How has Audacity found the level 19.1 in my case? Is that recommendation of the software?

I have the recording level - and listenig too - in maximum position.

Quite sure that I can manage mit Audacity for my own projects, but asking for better knowledge to help other users here in Finland.

Have you read Audacity Manual ?

By default, Amplify sets the loudest peak in the audio, whether that peak was originally -19.1 dB or -16 dB or whatever, to 0 dB. It does this by amplifying the entire audio by whatever dB increase makes that loudest peak 0 dB. 0 dB is the loudest level you can set your exported audio to without distorting it.

By default, Audacity will not let you move the amplification slider to right and apply the effect, because that would push the peak over 0 dB.

If you move the slider to left, “New Peak Amplitude” in Amplify will show you the resulting level of the peak that you will get when you apply Amplify.

If you are only volume adjusting one track at a time, you can try Normalize (“Normalisoi”) instead. Normalize does not calculate what amplification would be required to make the peak 0 dB. Instead, you choose the amplification to set the peak to.

So what amount of amplification does Amplify suggest - usually about -20 dB? If so it would be better to record a little louder than that, if possible, up to about -6 dB peak.

If the Audacity recording slider is greyed out and you cannot move it off maximum, go into Windows Sound to adjust the recording level of the cassette player.

To make louder recordings you might also connect from the headphones out of the cassette player to the stereo (blue-coloured) line-in of the computer. That only works properly if you have two audio inputs on the computer, one (pink) for a microphone and the blue input that is for a strong, stereo “line-level” signal. If you connect in that way, you can then turn the volume control up on the cassette player to control the recorded volume.

If you connect the cassette player from headphones out to the microphone input, you may get the opposite problem - recording may be too loud, so will distort, and may only be mono.

See How to connect your equipment - Audacity Manual.


19dB is a lot of gain, and I’m not sure why your signal is so weak. A line-level RCA connection from a cassette deck, or a headphone connection with the volume turned-up should be stronger.

How has Audacity found the level 19.1 in my case? Is that recommendation of the software?

It scans your file to find the current peak. It means your peak was -19.1dB before applying amplification. If you apply that change and run Amplify again, it will default to 0dB of change, which is no change.

Many thanks for your patience! Can I see somewhere how the peak amplitude changes when adjusting Amplification (dB) slider?

Hang on, it get’s complicated…

dB (decibels) are a relative, logarithmic, measure. In the “digital world”, the reference is 0dBFS (zero decibels full scale). In the computer, 0dB is essentially the maximum count you get with a given number of bits. That means that 0dB is a bigger number with 16-bit audio than with 8-bit audio. But the audio software takes care of scaling, so a 0dB 16-bit file is not louder than a 0dB 8-bit file. (You don’t need to worry about the underlying binary numbers unless you are a programmer.)

Since 0dB is the “digital maximum”, we are usually talking about negative dB levels.

Floating point files use a different numerical reference, there is essentially no upper limit and they can go positive. Audacity uses floating point internally so it can go over 0dB. But, if you go over 0dB and you export to a normal (integer) wave file, the waves will be clipped (they’ll have distorted-flat tops & bottoms).

When we adjust the volume for 0dB peaks, we call this “normalizing”. It’s fairly common practice to normalize (maximize) digital files. Most commercial CDs are normalized, or at least the song with the highest peak is normalized.

With acoustic sound, decibels are measured in dBSPL (Sound Pressure Level) and here the 0dB reference is the smallest sound humans can hear. So, acoustic sound levels are positive numbers. Although digital files and acoustic levels are measured with different dB references, they still correlate. If you are listening to your speakers at 90dB (SPL) and you boost the volume by 6dB in Audacity, the sound level will go up to 96dB. But, since every playback system is different and every system has a volume control we usually don’t know the exact relationship between the digital level and the acoustic sound level.

A decibel number can represent a relative level or a change… Your file is peaking at -19.1dB, so if you amplify it by +6dB it will peak at -13.1dB. So, although we are mostly measuring negative dB values, a change can be positive (boost or gain) or negative (reduction or attenuation).

BTW - If the peaks are boosted by 6dB, the average level is also boosted by 6dB… All of the samples in the digital file are increased by 6dB.

A change of 6dB is a factor of two. That is, +6dB is twice the signal level and -6dB is half the signal level. In a digital file, that’s double or half the digital value, and with an electrical signal it’s twice or half the voltage. 20dB is a factor of 10.

Just to further complicate things… Power (Watts) is related to the square of the voltage. So +6dB is 4 times the power, +3dB is twice the power, and +20dB is 100 times the power.

Also, the peak level does not correlate well with perceived loudness. Our ears don’t respond instantly and many quiet-sounding songs have short-term 0dB peaks. Loudness is more related to the average level and the frequency content… If you normalize all of your songs, they will not be equally loud.

OK. I think to be on the right tracks. Audacity will watch that user can not set too loud Amplifyer effect. So in normal circumstaces user has no problem to point OK for what audacity has put in Amplifyin (Vahvista) window. For my self 19,1 is the best solution, when that is not too loud. Is that so.

Can someting useful to be read from output meter when listening project (green-yellow-red wiht number scale meter)? Shall it show peaks reach to red?

Tomorrow I go to by new cabel to connect deck recorder to PC. I have allreary started to writing of old tapes digiting. Taking sreenshots of digiting with USB Casette Capture using Audacity. :smiley:

Yes, the default Audacity meters show an increasingly red colour as the volume gets higher than -6 dB.

They show a red clipping indicator at the far right once volume has exceeded 0 dB.

See Meter Toolbars - Audacity Manual.


Andrew, you wrote earlier of different ways to undertstand and read dB levels. Get used to understand positive dB metering. Maybe it is therefore that I cant fully understad it when set the voice level higher or down. For ex.: I have Audacity made 19,1 Amplifying with New peaks 0.0. You was doubting if this is loud inaf. In practice when using this settings Palyback Level meter goes to red indicator with both canals. To avoid this I have retuced Amplifying to 13.1 and peaks to -6.1. Using this setting the Palyback Meter goes between 6 to about 2 and there is not anymore red indicator to right. Have I that way made the Aplifying smaller, not too loud?

Remember that I will wrote of boht methods: digiting using USB capture devide and taperecorder. USB capture devices are here new and therefore must use also this method. My own musik C-cassettes is old but they are well recorded, from radio or other tapes. And 1-3 times recorded again always correcting sound levels using measuring of good taperecorders. Several test (Aucacity) with diffrent Amplifying levels is all quite good to listen with ears.

To morrow I can use also taperecorder using new cabel from recorders Line Out connected to blue line of PCs voice card.

In English, unlike for example Hungarian, the second part of the name is the surname.

0.0 is the loudest digital reference level that does not have clipping when you export. But remember, the peak level says nothing except what the peak level is. It does not tell you how loud the whole music seems to you.

If you had music that was at -20 dB except for one brief peak at 0.0 dB, you would probably think the music was not loud enough. In that case you would want to reduce the dynamic range of the music using Compressor.

The word in English is “channels”.

Leave “Allow clipping” in Amplify unchecked (no tick mark). Then the Playback Meter will not show the clipping hold indicator as long as you only have one audio track in Audacity.

If you have more than one audio track, their volume is combined, and so playing more than one track together may make the playback meter show the red clipping hold indicator.

If the New Peak Amplitude says -6.1 then the playback meters will not exceed -6.1 dB and so will not reach -2 dB, assuming you have only one Audacity track.


Gale, sorry about misstakes. I know very well English name pactice witch is same here in Finland. I only remember wrong that Andrew is your first name.
Have one friend wiht that name. Sorry also of my English. It is very poor. When I was youngster that time we stydy German in shools. Nowadays the situation is completely different here and in hole norden Europe. I try my best…

OK, connected taperecorder to PC. First a nice misstake. Have a new voice card, but connected first to old audio device. :smiley: Line in has pink color. Notist that taperecorder makes much “better” recording with Audacity as USB capture device. Using taperecorder I suppose it is no need of Amplifying effect. When opened it, Audacity has put Amplifying to 1.5, and peaks 0. Quite sure that I will use only taperecorder for my own projects.

But writing for othwer people: When there is cutting no allowed and the recorging meter shows in two channels (stereo) red marker, is that OK or reason to reduce recording level? How then when only left or rigt channel has red marker?

Which is the best method to correct right or left channels recordig, balance, what is very easy for ex. in taperecorders? Can it be made when recording or after that? That is maybe no problem of my own C-cassette recordings.

When I get someting ready are you interested to see sreenshots of my project or to read tape digiting article from my internet sites? It will be in Finnish and Google can make terrifying bad translation of it. (Finnish is very difficult language.)

What do you mean by “no cutting allowed”?

Clipping in one channel only is still bad. You may still hear it.

Audacity has no way of adjusting the balance when recording. Windows “Sound” or the control panel for your sound device might have an input balance control.

If you have to adjust balance after recording, the Normalize effect does that automatically if you enable its “Normalize stereo channels independently” control.

Don’t apply Normalize to multiple Audacity tracks if those tracks have intentional volume differences between them, because Normalize will remove those differences. Amplify will not remove volume differences between tracks if applied to multiple tracks.

You can post a link if you like, but there is no guarantee anyone will comment about it, especially if they have to work around a bad translation.

By the way, the first time you mention the word “Audacity” on one of your web pages, we would like it if you could refer to Audacity that time as “Audacity(R)” - the “(R)” is our trademark.


What do you mean by “no cutting allowed”?

Clipping in one channel only is still bad. You may still hear it.

I mean “Allow clipping” is not marked in Amplify effect. Also is it bad that there is red markes on both stero channels or one of them when lissning project test. Is it reason reduce recording volyme? No guestion of use clipping, only of red markers in measuring channels.

I think have allmost clear. Only using Apliyfy effect I will ask if this is acceptable. Here shortly the meaning in only few words:

When listen your project see the Playback Meter. If it reaches 6-3 recording volyme is OK. If the meter goes over it to 0, and end of the indicatos is red markes(s) ( cleared with picture) it is reason to reduce recording volyme. When indicators reaches not 6-3 levels it is possible to correct it with Ampliyfy effect (link to manual). When open it settings there is maximum correction. You cant make misstakes to set it any higher. Recommendation is to accept it by pointing OK. Test it. When you see now indicatos rise to 0 and you see red markes in end of meters, so you can reduce recording volyme by moving Amplification slider on left or writing new reduced reading to Amplify window (picture).

About that. Notist that in this case most of the readers are only interested to digit old C-cassettes by simpliest way. Users who will use Audacity more avanced way shall read Manual and study the software. I try to answer questions of my digiting cassettes article, if I get some.

You can enable “Allow clipping” by checking (ticking) the box, but the box is (correctly) unchecked by default.

I have already answered this. If you do not enable “Allow clipping” and only have one Audacity track then there will be no clipping in the recording meters.

If you are looking at View > Show Clipping (which shows clipping as red vertical lines in the waveform), that would show clipping if you amplified sine tones to 0 dB, because Show Clipping shows clipping if only one sample is “very close” to 0 dB.

The meters require four or more consecutive samples to be clipped before the clipping hold indicator shows.


Gale, good to know, thanks for that. I have no meanig write of peacks clipping in my article. Only write of some information using Playback Meter (and in same context Amplify effect). I still do not know what to tell about the red markers - one or two - if found in end of Playback meter. Is it reason to reduce recording volyme or not?

For me is most important that my description using it and Amplify effect is about acceptable. You have not commeted about on that.