eliminating hiss or hum

I have just started using Audacity and am still finding my way around. I am a PhD researcher and have a number of interviews which I want to convert from the Minidisc recordings to another form (such as mp3 or wav files) that I can store on CD or USB. The problem is that there is a hiss or humming noise which is quite audible when playing back the recording and was present on the original recording, possibly caused by the microphone connection. Is there any way of eliminating this to make the interview clearer? The continuous humming is not necessarily distracting but it is a little annoying! I hope you can help.

It depends on exactly what you mean by “hiss or humming noise”. You say the noise is continuous, so Audacity’s Noise Removal tool may help.

See: http://manual.audacityteam.org/man/Noise_Removal

If the problem is “hum” (not “buzz”) the Notch Filter effect may help: http://manual.audacityteam.org/man/Notch_Filter

Can you attach a short sample in MP3 format to a message here on the forum? Hearing exactly what you are dealing with will help us recommend a solution.

– Bill

Few of these tools magically know what hum and buzz is. They all use your instructions to surgically and blindly remove pieces of the show in hopes that what’s left is artistically valuable.

For example, if there is a lighting buzz component at 360Hz (common in the US), then a piano note at 360Hz (F#4 at 369Hz) may be damaged.

Most people don’t have hum. 60Hz and 50Hz are very difficult to hear (16’ pipes on the organ) but distorted 60 produces garbage all up and down the audible range. 60, 180, 360, etc. A440 is in the middle of the perceived orchestral range, so there’s the bottom of the orchestra in the trash heap.


Thanks to all the responses to my question regarding the above. Bill, you asked if I could send a sample - it is a clip that I recorded as a test but I haven’t converted it yet to MP3 - I haven’t got that far in the tutorial yet! However, I hope that you will be able to listen to it and if you can you will see what I mean. Having listened to it again, it sounds like more of a humm/buzz than a hiss. I didn’t realise that I was going to have to be that specific but having read all the responses, I now see that it might prove difficult to disentangle the noise from my interviewees voice without damaging the recording in some way. I am no ‘techie’ so please forgive my ignorance if I appear not to have got to grips with the terminology.
Ralph Hall test.aup (2.52 KB)

Unfortunately that file does not help.
An AUP file is not an audio file, it is part of an Audacity Project.
AUP files do not contain any audio data.
See here: http://manual.audacityteam.org/man/Audacity_Projects

Ok, I will have to re-post and attach the file when I have converted it to an MP3/Wav file. Back to the tutorial.

“WAV” format is preferred.