Microphonology

piezoelectric element

ceramic piece + metal piece. wires are solded ? on them

Also called a “contact microphone”.

Single coil

A coil of copper wires

Magnetic inputs are translated

We can listen to electric radiation.

ghost busters

There is a coil in the speaker, that creates membrane.

We listen to electricity when we put the coil near e. Devices

The membrane has electric coil inside, that start to pick up (?)

The

coil unit measure = Henry (H)

Why can’t we hear the things that the coil microphone picks up?

The coil is a spiral shaped thing… which creates a magnetic field. (made from which material?)

In an e-guitar, the string is moving in a certain frequency, and while doing that, it interrupt the magnetic field of the coil. And therefore, it creates an electric current.

This electric current needs to be amplified to be heard.

Henry unit: https://www.britannica.com/science/henry-unit-of-inductance

Electric current is not air vibrating.. instead it exists of magnetic waves.

The more coil, the more sensitive it is for magnetic waves.

It does not respond to air moving, but to magnetic waves.

You can speak into it though, as your voice will make the XXX move.

There are different terms used to refer to translating something into sound: “sonification” is a term being used to turn things into sound, and there is also the term “audibility” which acknowledges that things are already make sound, you need to translate it into something that we can hear.

in the field of electroacoustics

Coil picks up the vibration and starts to resonate with it.

Coils are used for amplifying, they are used pick up vibrations from the membrane.

EXAMPLE

When we put a coil mic on the power cable…:

• there is electricity in the power cable of 220 V, it vibrates on 50 hz (this is ⚡AC, alternating current, which means that it moves from +’s to -’s) (⚡DC direct current)
• we hear the AC, because the switching between +’s and -’s is influencing the current of the coil
• the mixer amplifies the signal
• the sound it send to the computer, where it is digitized: inside the computer there is an Analog to Digital CXXX (ADC)

bits

analog signal = wave (round formed wave)

ADC –> analog dicgital converter

digital signal = 0 1 (square formed wave) (bit is the resolution) (this is an one-bit signal)

https://hub.xpub.nl/soupboat/~grgr/static/img/ADC.png?_xsrf=2%7Ce1829a33%7C67ea12b43d416a8d3e480b4006c2b3e9%7C1648483743

1 bit = 2 steps

2 bit = 4 steps

4 bit = 16 steps

You express bits in khz.

For example: 48khz or 22 khz.

The more bits, the “better” the quality.

But this is relative, as some people really like 8-bit sounds for example.

hertz Hz

1 hz = one wave/second

15 hz = 15 hertz/second

frequency !

100 hz = 100 waves per second

this is a frequency of 100 hz

100 hz sounds lower

1000 hz sounds higher

the higher the frequency, the higher the tone

If you get older, you slowly cannot hear the higher part of the frequency spectrum anymore.

Everything over 10000 is harder for older generations to hear.

And generally you can hear from 100 hz/sec.

High frequencies are used as ringtones by younger people, as the teachers cannot hear them anymore.

High frequencies are also used as mosquito devices in the city (of Rotterdam) as a control device for public space.

https://hub.xpub.nl/soupboat/~grgr/static/img/signal_gnd.png?_xsrf=2%7C56b1ca45%7Cb97e62b249915279b4aabb03c868875f%7C1634591706

dynamic microphones

The dynamic microphone (also known as the moving-coil microphone) works via electromagnetic induction. […] Dynamic microphones use the same dynamic principle as in a loudspeaker, only reversed. A small movable induction coil, positioned in the magnetic field of a permanent magnet, is attached to the diaphragm. When sound enters through the windscreen of the microphone, the sound wave moves the diaphragm. When the diaphragm vibrates, the coil moves in the magnetic field, producing a varying current in the coil through electromagnetic induction. A single dynamic membrane does not respond linearly to all audio frequencies. For this reason, some microphones utilize multiple membranes for the different parts of the audio spectrum and then combine the resulting signals. (Wikipedia)

SM58 microphone

Looks like a speaker, and it is actually a speaker.

With a microphone you get the current, with a speaker you give current.

If you speak, the membrane starts to vibrate, this creates a current in the coil, the coil then gets pre-amplified in the mixer and the audio output.

“the current in the coil”

This microphone is similar to the coil e-guitar microphone, as it is also based on coil.

Jack connector

You can open it.

The “tip” picks up the signal.

The larger pipe is the “ground”.

When you solder the piezzo mic, you connect the black cable (the ground) to the ground of the jack connector.

What medium do you use to communicate?

Medium of air

Medium of electricity

microphone: vibrations into signal

Electrical signals are always about difference: you always need to measure the signal and the ground. You need the ground to understand what/where the signal is. It’s a point of reference.

Soldering

You can solder a piezoelectric or coil microphone.

You need: jack connector + microphone of choice + cable.

A cable is a set of wires with plastic around it. Two cables cannot touch each other. The plastic also protects the cable from picking up electromagnetic waves, to make sure you pick up a “poor” signal. This is called “interference”, which is the unwanted picked up signals, which people like theater producers strongly fear while working.

Step 1: strip your cable

Strip the (black) plastic from the end of your cable. It does not matter how much you take off, but 2 cm is useful.

They have a great tool downstairs in the interaction station, called a stripper, to take the plastic of the wires.

Once you opened it, you will find a blue and red cable.

Step 2: place the cable in the jack connector

There are two square parts on the end of the jack connector. In between, you can put the whole cable.

Take a tool (“knijptang” in Dutch) and push it together. This is just to hold it.

Step 3: isolate the red and blue cables

Isolate the red and the blue cable, this means: take a bit from the plastic from the ends of these cables.

Pick a small cutting tool, and take 5mm of the plastic from the ends of the red and blue cable. You can also do this with your finger nails, but make sure that the two cables (the red and the blue) do not touch each other!

Now you see the small wires.

Step 4: solder the cable to the jack connector

Take the solder material.

It melts at 320 Celsius degrees.

Just take a little of it, like 30 centimeters.

Take a third hand.

This is a device with little teeth that you can use to put your wires in.

Take the soldering iron.

You don’t have to use it like a pen, you just need to heat up the things you want to solder.

Don’t touch the tip of the soldering iron! It’s super hot.

The idea is that you heat up the wire, and once you place the soldering material to the wire, it will solder itself.

This is “tinning”: heating a piece of metal (the connection point), then touch it to the solder, and then it connects the two together.

Connect the red cable to the upper small hole (the one closest to the tip of the jack connector).

Connect the blue cable to the lower one (the one closest to the square holding piece at the bottom of the jack connector).

So, let’s solder!

First: Heat up the cable for 3 cm (tinning).

Then: Put the solder material to the cable.

Step 5: solder the cable to the microphone

Isolate the other side of the red and blue cable.

Cut 1 piece of** blue shrinking tube**, something like 2cm (the wider one).

Put it on the main cable.

Cut 2 pieces of white shrinking tube, 5mm each (the more narrow one).

Put one of the red and one on the blue cable.

Place the main (black) cable into the third hand.

Seperate the blue and the red cables, to make sure that they do not touch each other.

Heat the red and the blue cable and put some solder on it.

Heat one of legs of the microphone and put some solder on it.

Do it closely to the microphone itself, the legs are a bit too long.

Repeat this step for the other leg of the microphone.

So now, you have solder material on both cabled (red and blue) and on both legs of the microphone.

Because there is material already on both the cable and the leg of the mic, you only need to heat the solder material up a bit and it will connect the cable to the mic.

Now we are ready to solder the cable and mic together. Put the mic in the third hand, to make it easier to solder.

It does not matter which cable is connected to which microphone leg.

Heat the material on one of the legs a bit and connect one cable.

Repeat this for the other leg and cable.

Now put the white shrinking tube around the place where you connected the red cable with the mic.

Heat the shrinking tube by putting the soldering iron onto it, so it will shrink around the cable and protect the connection.

Repeat this for the blue cable.

Now first test your microphon!

Put it into the mixer.

To test a coil microphone, you can place it onto a phone, where it should pick up some electromagnetic waves.

To test a piezo microphone, you can place it on the table and knock, or place it to your neck and speak, to pick up vibration.

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If it works, you can continue. If not, you can look at your soldering connections again to make sure they are connected well.

Now put the blue bigger piece of shrinking tube onto the part that you just soldered.

Heat it up with the soldering iron to shrink it.

Recordology + Audio-Editorology

We rented two ZOOM audio recorders from the WdKA rental for this week.

You can find the WdKA rental on the ground floor on the Wijnhaven side, and also see what they have here: https://rental.mywdka.nl/.

Where is the rental? Upon entry of Wijnhaven, keep left. Up the stone steps, through the corridor.

More information about the rental can be found here: https://static.mywdka.nl/facilities/rental-shop/wdka-rental/

One basic rule with recording: the level should not go above 0db, and a lit a bit under 0db; so you can see the levels going up and down.

echo echo echo echo echo

You can record in mono and stereo.

Spectogram

Maps time (horizontal) and frequencies (vertical); you see that the voices are happening on different frequencies at the same time. Looks like an abstract painting/tapestry.

Some composers draw images with spectograms, as a way to make sound. We will come back to this in the coming weeks.

An example: Venetian Shares - Look (from songs about my cats 2001).

https://www.youtube.com/watch?v=BHup81lEjqo

Another musician that did this was Aphex Twin: https://www.youtube.com/watch?v=M9xMuPWAZW8

Around 5khz the signal becomes almost white.

http://lesportraitsaudacieux.blogspot.com/p/on-en-parle.html

Equalizer

You can work with an equalizer.

to clean out the noise in a recording

equalization:

inside the equalizer you can see the different frequencies of the audio piece. you can use the equalization to filter frequencies that you don't want. or to isolate and improve the ones that you want.

Audacity

Audio editing

Simple audio editing software. It’s free software, you can install it on your computer, follow the instructions here: https://www.audacityteam.org/download/.

manuals for audacity https://archive.flossmanuals.net/audacity/

you can make glitched images with it

and look at the spectrogram of audio

When you record in Audacity, your recording is too loud when the blue waves touch the top and bottom.

Question: It is possible to add channels, voices etc, like the layers in photoshop? yes.

Question: How to blend multiple voices into one piece of sound? file > export> .wav format

wav: high res file format, uncompressed.

mp3: low res file format, suitable for the web as it is less big in terms of Mb’s; compressed file format

ogg: another low res file format, also suitable for the web; compressed file too

Small anecdote: Spotify only streams music in low res file formats, to not make it too heavy.

Save your audio to file

1. export > wave .wav
2. encoding: signed 16-bit PCM (this one is fine)
   • #** the more bits, the more quality you have
   • #** the pixels of the audio file
3. save

Questions

Why can decibels be negative?

Why are the waves of the analog signals so organic? And the digital ones are square?

A 1 bit digital system only can save data in 2 states: 1 and 0.

A 16 bit system can save data in = 2^16 states = 65536 states in total.

How to record (maybe this part should go to recordology? for later):

1. avoid to get to close to the microphone, otherwise you get the socalled pop effect. (you can see that the green line that signals the sound volume turns red (clipping)
2. check your setting in your os: sometimes you get a square-ish wave in audacity, that means that your input level in your settings / system preferences is not balanced
3. when recording in audacity, look at the horizontal scale on the top: the sound input should be close to 0 decibel but never actually reach 0 decibel (you will be in the orange-red-zone if you are too close) [the vertical scale of each sound wave (-1.0 to +1.0) shows the frequency (=amplitude per second?), which is not the same scale as the decibel]???? nope decibel db is the volume so to say and the frequency is in hertz Hz but the -1.0 +1.0 scale is neither decibel nor hertz right? i guess not, right thx I’m not sure but i though 1 and -1 has to do with the fact that waves are seen and drawn in graphics only between 1 and -1 in mathematics aaaaah so you see the shape of the wave but it’s frequency and the amplitude is mapped onto this range of -1 and 1.
4. watch out when you add up multiple tracks in audacity (the same track multiplied twice and played simultaneously will duplicate the amplitude of the sound (volume)) why the microphone understands the power supply frequency??

there’s a mixer that converts AC into DC and it gets the 50hz freq

if the mixer lacks of a filter called (???) it might happen that you hear the electricity that gives power to it

to filter noise in the rec:

select a profile for the noise (literally select the part of the audio where there is a moment of silence and you can only hear the noice you wanna filter) 

then goto >filter>noise reduction> get noise profile  then select the entire piece of audio and again >filter>noise reduction>ok 

effects with audacity

loops

select a piece of audio, effects>repeat> …choose the n of repetitions you want

stretch

select a paulstretch from the effects menù

reverb

reverse

recording studio notes

XPUB PC

• password: opisop
• software: Audacity, Rack (synthesizer software)

Mixer

• XPUB/PC: the input coming from the computer
• the black L/R cables at top right: output to the speakers
• red knobs: the connection back to the computer (for recording with a microphone)
• orange nobs: the connection to the osciloscope
• black knobs: controlling the left and right
• MIC1: the left fader is to control the volume to the speakers

About recording with the microphone: currently you can only record mono. We are missing some cables at the moment. Maybe we can do some changes next week and allow for mono recording. Joak is ordering cables, Kamo can bring some that can be used in the meantime.

About the effects: the effects on the mixer make weird noises

Audio interface

The red box is Kamo's and can be used to mix multiple audio inputs at the same time.

Transcodology

transcoding = convert a digital file

for example from .wav to .mp3

.wav = very good quality, big file

.mp3 = less quality, smaller file

similar to converting images from .tif to .jpg

Using FFmpeg

Notebook with examples: https://hub.xpub.nl/soupboat/SI18/documentation/ffmpeg/

Also available on paper ;).

Before we start with this part

Upload your recording to the soupboat: shared/html/SI18/00/recordings/

Which you can see from the “outside” here: https://hub.xpub.nl/soupboat/SI18/00/recordings/

When doing ffprobe

Mp3’s can be compressed in different ways.

cpr

bpr

If the bitrate is very high, the filesize is more, and the quality will be better.

We can look in the upcoming weeks to look at very low bitrate, the lower the glitchier bit rates, to see what it does.

It is a way to learn about the Mp3 compression algorithm.

The visual sister of Mp3 is JPEG. Which is also a compressed image format.

What is the recommended bit rate for Mp3s?

128kb/s is normal, good quality. standard settings usually make tiny files but good quality

Does changing the frequency have an impact on the sound?

Depends. It can make it slower or faster.

How to change the bit rate?

add -b:a to the ffmpeg command

compression –> see notebook on the soupboat “transcodology”

Publishology

The issue website for SI18: https://issue.xpub.nl/18/

Upload the release to the soupboat in shared/html/SI18/00/: https://hub.xpub.nl/soupboat/SI18/00/

Update the issue webpage through git: https://git.xpub.nl/XPUB/SI18

Ghostology

https://www.youtube.com/playlist?list=OL+K5uy_kofB1UsJ_37_0e0WcY2kJKf68XIWBNSn8

Documentology

try to make a mini template for things we need

This is a guide, feel free to reply to the structure as you want.

title (eg.: Emma in a garden)

duration

description [one sentence summarise] (eg.: we want to record two parallel diaries of environmental sounds]

score [prompt, general overview] (eg.: we record diary entries)

input [raw material] (eg.: audio recordings)

tools [used but not seen/heard everything /from tools to softwares/ used to obtain the material and modify the material] (eg.: microphone, audacity)

process log [steps, process, curation] (eg.: 1. record audio 2. upload files on audacity 3. normalise effect on audacity; 4. export)

output [public outcome] (eg.: link to recording)

who? [the person/group that worked on it] (eg.: Emma and alex)

Documentation Logs

gives a rhythm to the whole piece

set the ground at the beginning with the introduction

the different tones of voice position in different mental places

two people in a different place, home-travelling, contrasting experiences

episode structure

audio levels

time and place need to be clearer to hear, voices are meant to be legible

add a unified piece at the beginning like "day one" to set the space for the audience

   A pattern is a regularity in the world, in human-made design, or in abstract ideas. As such, the elements of a pattern repeat in a predictable manner. A geometric pattern is a kind of pattern formed of geometric shapes and typically repeated like a wallpaper design. Any of the senses may directly observe patterns.

   The pattern of instruction is uneven in this text. We are giving a list of instructions not following the basic rules of the type of text: they are broken down, disordered and messy, not linear, neither clear nor straight. It is related to the language pattern more than to a sound pattern. The computer voice gives a non emphatic interpretation of the text.

It doesn't matter which part is connected to which.

you always need to measure the signal and the ground. You need the ground to understand what/where the signal is. It’s a point of reference.

How to record:
       1. Get close to the microphone. You want to obtain the socalled POP effect. (put a pop song in a concert here)
       2. Check the waves and if they make a  balanced sound. (put a sea waves recording here)
       3. (yell) The sound should not be close to 0 decibel and always reach it. 

To blow your nose:
   1. Select your best profile side (literally select the part of the face where you look better)
   2. Go to your drawer > open it > get a tissue >  put the tissue on your entire nose > blow your nose > done