I am a senior lady with some computer skills. However, I am new to audio. My husband of 58 years just passed away and I am going through my computer & realizing that I must pass on to my 4 children, 9 grandchildren & 3 great grandchildren all the .jpg files and sound files I have saved for them for the past 50 years. I have this old cassette tape that I converted to mp3 but the organ is so loud you can't hear the kids singing. Is there anyway to lower the sound or even take it out all together so they can hear themselves. Thank you.
You can sweeten the audio to a point, the most direct way of doing so would be to go back to your cassette tape; and to re-convert it to a 24 Bit WAV or AIF file.
MP3 files are highly compressed. So for best results; you are going to want to go back to your analog source and recapture into a file format (listed above) which will give you the largest dynamic range possible. (24Bit 96kHz WAV or AIF is fine).
Working off your MP3, regardless of the quality/bitrate it was encoded at, is a weak starting point.
Second Step; the file needs to be run through an audio processor. There is a free tool called Audacity; which is honestly excellent and it's freeware- just google it, and it supports the file types I've mentioned above. However, it lacks the easy to use graphic user interface and control surfaces that make doing what you want "easy". But it can be done. It also allows you to output/save an MP3 as your final file.
Whether you work with the free program Audacity, or ProTools (expensive); or even in a program like Premiere Pro (Video program with audio tools built in): My recommendation would be to:
First: Add Dynamics and Compression. You want to compress the the dynamic range at least some, and expand the areas where the dB level is low. This will provide you with a more "even" sounding recording-- which is not the same as MP3 compression. It still will be treated as full uncompressed audio in terms of down the line effects.
Secondly; all you really will want to do (lacking very expensive tools and plugins), is after you first add your Dynamics/Compression -- is add a series of Equalizers in a chain to the file.
Visually, you would set one of your pots (knobs), to a specific sonic frequency. For example, lets say you want to eliminate the lows (well under middle C). You would dial in a low frequency, then set your Q, which is how "narrow" the effect, or wide for that matter, will be applied to your audio file.
You start with a very narrow (all the way as far as it will go), Q. This creates what looks like a spike, either up, or down, as you turn that particular frequency either up or down.
If you had a wide Q, it would look more like a speed bump, and would affect a wider range, depending on how large your Q is. But you want the Q as small as possible. Like a spike straight up (when you EQ'd it all the way up or down).
So you set your frequency (call it the hunt... what you're looking to eliminate), set your Q as narrow as possible, then turn up the gain on that frequency all the way. Max out.
Next, slide the frequency (which you first guesstimated on the low end) slowly up and down, with your Q all the way narrow, and gain all the way up.
You slide it up and down, looking for the "sound" you want to eliminate. You will distinctly hear it. You can use this process to remove specific notes. You just have to find them.
Once you find that really annoying sound (it will sound annoying if it's what you are looking to eliminate - because you've turned what you "dont" want to hear all the way up). This is when you simply drop the gain back down below normal... about 4-18 db depending on how much you want to take out.
You do this over and over, until you get the best result possible.
Audacity can do this, but it might be painstaking without visually being able to see it like in a paid platform.
Lastly, the areas of difficulty, will be where the children are in the same sonic and tonal range as the organ. Same key. You can't remove one without the other.
Hopefully not too overly complicated what I've said. Get it re-encoded into an uncompressed file. And run it through an EQ. (Adding Dynamics first if you can).
EQ, EQ, EQ, until you get the result you want. Working with an uncompressed file, you can EQ a 100 times over with no loss in quality.