Image courtesy of Wikipedia, http://en.wikipedia.org/wiki/Alger_Hiss

Remove hiss in audio recordings

Got great equipment? Tried everything, but still have hiss in your Mac OS recordings? Check this out!

Background

I recently bought “the stuff” that pro podcasters use with an eye toward creating the Tech Comm Tools podcast. I got:

  • A high-end Heil PR40 microphone
  • An equally high-end Mackie 1402VLZ4 mixer
  • A boom stand with suspension mount
  • A pop filter

For visuals and details see my Podcasting Setup

And while all that’s great, when I hooked it up, I ended up with an audible high-frequency hiss (or ringing or hum) in my end of interview recordings.

While I can filter out the noise in post-recording editing, that’s kind of against the whole concept of buying quality stuff!

I had a sound engineer double-check my setup, played around with cables, usb input devices, and have been spending a ton of time on web searches to find out a solution. Nothing helped.

Every few weeks I’d try a different search, and I finally ran across a hint to my solution at

https://apple.stackexchange.com/questions/42743/macbook-pro-creates-soft-hissing-sound-through-headphones/144035#144035

The solution

In OSX, open the Audio MIDI Setup application. If you don’t know where it is, just use Command+Space to use the Mac’s Spotlight feature.

Screenshot 2014-09-03 11.20.24

In my case, the offending setting was the input from my mixing board, which goes into a Griffin Technology iMic USB Audio Device. By changing the Format to 20,000 Hz, with 1ch-16bit Integer I was able to virtually eliminate the hiss/ringing.

So, how did I arrive at that setting? While I would have liked to go to a higher frequency, I found that the higher numbers introduced hiss/ringing, and that the lower numbers started to sound hollow and aquarium-like. Once I arrived at the optimal frequency, I found that the 1ch-16bit Integer setting was the best-sounding of the three choices.

Since I’m just recording voices, I’m not concerned about stereo input (one channel), and I’m not recording original music (which would suffer from the 24,000 Hz setting) it looks like I’m good to go.

If this didn’t help you…

You may instead need to adjust the settings for your output device. I’d recommend the same process of stepping through the available frequencies, then testing the channels and bit depth.

Of course, the input and output connections, cables, and devices themselves may also be an issue.

In my case, I was able to isolate the offending setting once I recognized that the hiss only occurred when I recorded the input from the mixing board. The microphone connection to the mixer (XLR) sounded fine, especially through reference headphones, but as soon as I chose an input device in recording software, the hiss would appear.

In any case, isolating the equipment is the first step. Once identified, you can then assess cabling, connections, grounding/power supply.

Let me know if this helps, or if you have tips on remedying other input/output issues.

Credit where credit is due:

My thanks to Bart Arondson, an expert at apple.stackexchange.com for pointing me in the right direction.

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