Apollo 16 unexpected sounds?

[Luckmeister]

Electronics are sometimes sensitive to mechanical vibration, a phenomenon naturally known as "microphonics" that is especially common with vacuum tubes used as low-level audio amplifiers, but I'll have to watch the video in question.

And not just from vacuum tubes. It could happen with solid-state as well, but less common.
Edit: I just noticed you basically said that. I need to wake up - it's early here.

And also, from Wiki:

Wiring and cables can also exhibit microphonics as charged conductors move around, and various materials can develop triboelectric ("static") charges that couple to the electronic circuits.

[JayUtah]

I'll buy the microphonics explanation.  The ambient cabin mic was deleted as part of the LM's weight reduction.

[bknight]

Electronics are sometimes sensitive to mechanical vibration, a phenomenon naturally known as "microphonics" that is especially common with vacuum tubes used as low-level audio amplifiers, but I'll have to watch the video in question.

And not just from vacuum tubes. It could happen with solid-state as well, but less common.
Edit: I just noticed you basically said that. I need to wake up - it's early here.

And also, from Wiki:

Wiring and cables can also exhibit microphonics as charged conductors move around, and various materials can develop triboelectric ("static") charges that couple to the electronic circuits.

I'll buy the microphonics explanation.  The ambient cabin mic was deleted as part of the LM's weight reduction.

I thought it might be vibration, but to anyone, what was it vibrating into, given there is no microphone in the LM?

[JayUtah]

I haven't see the video, and I won't be able to until late tonight.  It would depend on where on the LM the impact occurred.  Most of the actual comm equipment was on the cold rails in the aft equipment bay.  But that stuff is always heavily potted.  I can imagine certain components that incorporated embedded dieletric layers, and were potted only insofar as their casings, might generate a single if vibrated.  But without that, you're left with wiring harnesses to the antenna arrays and to the headset connectors in the cabin.

[bknight]

I haven't see the video, and I won't be able to until late tonight.  It would depend on where on the LM the impact occurred.  Most of the actual comm equipment was on the cold rails in the aft equipment bay.  But that stuff is always heavily potted.  I can imagine certain components that incorporated embedded dieletric layers, and were potted only insofar as their casings, might generate a single if vibrated.  But without that, you're left with wiring harnesses to the antenna arrays and to the headset connectors in the cabin.

I'll give you a Readers Digest, the impact isn't seen, just heard.  But I can estimate the impact is towards the top of the LM.  You'll see what I mean when you watch.  Let us know what you think when you do see the clip.

[ka9q]

I doubt anything hit the LM. It's just one of the many little communication artifacts in the Apollo missions.

The astronauts' VOX-triggered microphones fed a long chain of communication channels starting with their backpack radios, the relays in the LM or LRV, the large ground stations (which handed off every 8 hours as the earth turned), a large network of satellite and submarine cables, the NASA network (based at Goddard, I believe), and so forth. Every one of these links, unlike today, was analog and capable of injecting its own interference. All were active even when the microphone VOX was closed.

[bknight]

That was probably true, but it allows the HB's to have an anomaly at their disposal.  I still wonder about it myself, even though I know the throw occurred and a noise followed shortly afterward. 

[nomuse]

Seems the conservative explanation that this was a spurious and co-incidental sound.

Reminds me of when I'm mixing a live musical with 20-30 live body mics plus pit, and a director or someone will come back to me and say "You need to fix Tony's mic -- we heard a noise during his line."

[bknight]

After reading all the way through the form I linked, I found the original video in the ALSJ
http://www.hq.nasa.gov/alsj/a15/a15v.1205113.rm
It is has a real media format and I don't know anything about conversion to a YT, but here it is.  Look around 1:45 for the thrown object.

The comment that it is a real media format may be misleading, from ALSJ RealVideo Clip:. 

[JayUtah]

in the clip, the sound seems to occur while the object is still moving.

[bknight]

I don't get that impression, the object is off screen when the sounds occurs, so movement/hitting is not able to be determined.

[ka9q]

I still think it very unlikely that an astronaut would deliberately hit the LM.

[inconceivable]

There are a lot of sound artifacts on the Apollo 16 lunar liftoff.  It's like there is an atmosphere around the LEM.

[bknight]

I still think it very unlikely that an astronaut would deliberately hit the LM.

I would agree with your thoughts, but have you looked at the video?  The object leaves Irwin's hand and head towards the Falcon, whether by purpose or lack of dexterity with the lunar gloves.

[Zakalwe]

There are a lot of sound artifacts on the Apollo 16 lunar liftoff.  It's like there is an atmosphere around the LEM.

"LEM"- noted.

There was an atmosphere IN the LM at liftoff, plus the rocket motor protruded into the cabin. I'd expect it to be anything but quiet!