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5 votes

Do kids under a certain age not hear the warning beeps that smoke detectors make when they are running out of battery power?

Unless they have hearing loss, young people tend to be able to hear a larger range of sound frequencies than older people, particularly higher frequencies: Some security companies recently began ...
Fred's user avatar
  • 9,687
4 votes

Why would a "delayed loudspeaker" be so expensive in the 1970s?

The band was the Grateful Dead and the invention necessary was an analog delay line that was inserted between the main audio mix signal line and the power amps that drove the speaker arrays (which ...
niels nielsen's user avatar
3 votes

Is it possible to measure the "noise level" of an area without using actual microphones which can record actual audio?

How do you define a microphone? Because there many ways to detect mechanical vibrations, but all of them could fit in a more or less relaxed definition of microphone. For example, you could measure ...
Adrian Maire's user avatar
3 votes
Accepted

Arduino DAC to Speaker

Your understanding of the issues is good. Q1: It's not overkill at all. All of the elements you've mentioned are needed. Q2: The low-pass filter frequency needs to significantly attenuate all ...
Graham Stevenson's user avatar
3 votes
Accepted

Why does audio equipment buzz/humm when a long signal cable is used and how do I eliminate it?

The reason for the humming noise is improper grounding. Audio signals are low voltage level AC signals (over simplified). An audio signal could be for example 1V, 1 KHz signal. When there is improper ...
Mahendra Gunawardena's user avatar
2 votes

Microphone angled waterproofing

You could make a water drain trap. Drill a vertical hole that meets the microphone hole somewhere along its length, with a drain hole sloping down for the water to escape. You could then make a step ...
alephzero's user avatar
  • 12.5k
2 votes
Accepted

Using the bitrate value on a calculation is causing contradiction, why?

Because the file is compressed. The sample rate and bits per sample are parameters of playback after decompression. The file size is for the compressed format, the amount of data that needs to be ...
SF.'s user avatar
  • 6,105
2 votes

Why does audio equipment buzz/humm when a long signal cable is used and how do I eliminate it?

That long audio cable is acting like an aerial. Does it run close to any mains wires - in the wall perhaps? You will be better off getting a quality shielded audio cable as a first step. If that ...
Solar Mike's user avatar
  • 15.9k
2 votes
Accepted

How can I calculate the total signal level (noise) of PC fans?

This is a pretty straightforward calculator: https://www.engineeringtoolbox.com/adding-decibel-d_63.html Basically noise level is dictated by your 2 loudest sources, so 50 dB + 40 dB (assuming they ...
jko's user avatar
  • 2,347
2 votes

What causes the hiss from one audio source but not another over long cable?

I will first assume you do not have any of the wires crossed here. It is unlikely that the cause is in the CAT6 cable, but here's how to test this: send the alexa signal (red) thru the cable to the ...
niels nielsen's user avatar
2 votes

Does Bitrate on sound files refer to bit/s or byte/s?

what you are calculating is the uncompressed bitrate. However, MP3 uses lossy compression, typically achieving final sizes of about 10% compared to the uncompressed file (for constant bitrates). ...
NMech's user avatar
  • 24.4k
2 votes

Is it 8 kHz the minimum number of samples per second and can that be written into a sound player?

Can you have a lower sampling rate? Yes. Wll it perfectly reproduce the original sound? No.
Solar Mike's user avatar
  • 15.9k
2 votes

How did this tape recording possibly happen on a technical and logical level?

This is very easy to do if your tape recorder had a recording function called "punch in". This lets you switch from playback straight into record mode without first stopping the tape. So, ...
niels nielsen's user avatar
2 votes

Mackie CR3 bookshelf speakers only play incredibly quietly on max volume

This is a standard issue diagnostic issue. We could send you to an audio equipment SE but diagnosing issues is what I do for a living. You say you have already checked most of these but the order I'd ...
user1683793's user avatar
  • 1,030
1 vote

Is it 8 kHz the minimum number of samples per second and can that be written into a sound player?

The problem is with the audible frequencies to the human ear. A good human hearing goes from about 30Hz up to 20 kHz. If you capture at 8 kHz due to the Nyquist theorem you can only reproduce ...
NMech's user avatar
  • 24.4k
1 vote

Why do the "LINE OUT" connectors not seem to output audio, but "HEADPHONE JACK" does?

Figure 1. The user manual diagram suggests that the line out L/R are (RCA) phono sockets, not 3.5 mm jacks. Figure 2. Phono to jack adaptor. Image taken from Google image search. Figure 3. Phono ...
Transistor's user avatar
  • 10.9k
1 vote

Is it possible that room noises could end up on the recording when recording audio from an analogue source?

Unless the room noise is loud enough to cause physical vibrations in the playback head, leading to misalignment of the head vs. tape track (which could cause crosstalk or amplitude dropoff), there's ...
Carl Witthoft's user avatar
1 vote

How does microphone -> software work?

Your question is the essentially the same with the following: How does the output of a microphone (an analog device) gets transformed to digital data that a computer (a digital device) can process? ...
NMech's user avatar
  • 24.4k
1 vote

Is it possible to measure the "noise level" of an area without using actual microphones which can record actual audio?

IMHO, if you use a device that can detect noise level if you program it in some way then it will be possible to program it in some smart way to record conversations. Personally, I don't think that ...
NMech's user avatar
  • 24.4k
1 vote

Is it possible to measure the "noise level" of an area without using actual microphones which can record actual audio?

You can measure noise level in decibels with sound level meters that give an instantaneous reading of the noise level without recording the actual audio. Prices vary, but there are even free apps that ...
jko's user avatar
  • 2,347
1 vote

Is it possible for a microphone/sensor to detect soundwaves before it physically reaches the sensor?

The speed of sound is not a constant. The speed depends on the material the sound is traveling though. The speed of sound in aluminum, for instance, is roughly 20 times faster than air. If the ...
Eric S's user avatar
  • 915
1 vote

Why does audio equipment buzz/humm when a long signal cable is used and how do I eliminate it?

As mentioned the cable is acting like an aerial. A ferrite core to wrap the cable around a couple of times might help. The comm to the charger comm is grounding it with less resistance as the other ...
Colin Ellis's user avatar
1 vote

How can I calculate the total signal level (noise) of PC fans?

The standard rule of thumb for adding decibels is that doubling the sound power increases the dB reading by +3dB. Using an on-lone calculator for adding dB's, we find that adding two sound sources ...
niels nielsen's user avatar
1 vote

Microspeaker enclosure design for headphones

the equations scale linearly for the linear dimensions of enclosures. However, here is why micro-enclosures don't get designed according to the same laws and equations used for full-sized speaker ...
niels nielsen's user avatar
1 vote

Making my microcontroller transmit audio to any bluetooth headphones/speakers

There are Bluetooth adapters available which will hook into audio system via 3mm jack or optical jack and broadcast the music to your headset. However if you want to receive the music into your phone,...
kamran's user avatar
  • 22.5k
1 vote

Adding an R2R Digital to analog converter inline with TRS connector

Okay, I will go ahead and answer my own question. Since I'll have to deal with an analog signal anyways, coming from the audio output of a mobile device. I'll need an ADC [analog to digital ...
user1610950's user avatar
1 vote

Microphone angled waterproofing

Why have the hole perpendicular to the front surface? Angle the hole so that it is slightly uphill when the screen is at the angle as shown. Or, could you fit a membrane on the surface of the ...
Solar Mike's user avatar
  • 15.9k
1 vote

Could a magnetic audio tape recorder/player be made using a vibrating permanent magnet?

Magnetic force microscopy should have sufficient resolution. The principle of operation here is that an external force causes a very small (few micrometers) magnetic probe to vibrate, and then the ...
Daniel K's user avatar
  • 2,646
1 vote

Could a magnetic audio tape recorder/player be made using a vibrating permanent magnet?

No. The magnetic flux density available on a tape is way to small to move a magnet with any significant mass enough to produce audible sound.
agentp's user avatar
  • 949

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