Audio problem: muffled, quiet VHS conversions?
 

I have about 16 vhs tapes that were given to me to transfer over to digital. All of the tapes have the same audio problem it seems the audio is very muffled and quiet. I have the same problem with my JVC S7900U as well as my Panasonic AG 5710. My guess is there original vcr did not record the audio track properly.

I wouldn't call it "quiet" but it certainly is lacking high-frequency response. Perhaps this is linear track audio?

How would I fix that?

If there is no hi-fi track and that's what the audio sounds like, that is all you have to work with.

Is there a way to fix the audio problem in Audacity? It seems like I hear music then dialogue, but not at the same time.

I am starting to think my Matrox MX02 maybe the problem with the audio or my pc. I even tried recording the audio through the line in on my PC with the same muffled sound. When I play the audio straight from the VCR into my Sony PCM-M10 audio recorder the audio sounds detailed and rich

Well, the audio appears to be mono, and thus likely from the linear track.
Was the recording SP, LP, or SLP/EP speed?
Opening the .WAV file in Audition, the high frequency cut off is around 4500 kHz. (See attached frequency plot.) The left and right are essentially identical (within 0.05 dB) no blue trace, thus mono.)

Quiet implies a low record level on tape but can be adjusted in post. It also means a higher noise floor.

While at SP speed the linear track is nominally rated to perhaps 10kHz, about AM radio quality. However, at SLP/EP speed the linear track frequency response drops to about 5 kHz on a good day due to the 3x slower tape speed. (It would be worse except for different equalization.) Something less than traditional AM radio quality, but better than traditional analog telephone.

Add to this possible variations in audio head alignment between the recorder and playback machine (which can kill higher frequencies), and the original recording environment, getting good audio off the tape can be a challenge.

As you noted using a different audio recorder or capture and listening environment may give you a more satisfying result. You also could try some combination of filters and equalization in post to try "improve" the sound; e.g., filter out the high frequency (above 5 kHz) that is mainly noise and increase some of the mid-high frequencies that are present. Just be sure you have a decent audio monitoring setup to evaluate your results (most TV sets and typical small computer speakers are notoriously bad for this).

The tape was extended play.

Music "ducking" under voice could be an intended "voice over" effect (found in more sophisticated video recordings), or just the action of AGC with a home recorder when the voice is louder at the camcorder's microphone than the music.

The recording frequency analysis is about what I would expect from a linear track at EP speed.

Then it's not the tape or how it's being played. Is it possible you are mixing stereo to mono with the MXO2? If the channels are recorded out of phase (a production error), then mixing them would produce the low, dull sound you are hearing.

Audacity can work for some issue, but Sound Forge is more powerful -- especially to recover highs/mids. What you're hearing is just typical analog tape, either copies-of-copies (nth gen VHS) or plain ol' crummy broadcast/cable. The original VCR is unlikely to have done that much audio damage. It depends on deck age. Anything from 70s-80s, maybe. Anything from 90s, not likely. Anything from 00s, perhaps; lots of EOL crappy decks from Funai/etc.

Note: I usually try to fix samples for Premium Members. (Must turn off AC, fix during night/quiet hours, etc.)

You are right. I believe it was from poor quality TV broadcasts.

For people looking at this in 2023. I solved this by calibrating the audio head in a similar VCR as OP. It had three screws and I manually adjust them until I found a good sound (to my ears). Note that for perfect calibration, it's better to use an oscilloscope.