soundspeakers
I know this is kind of a lame question, but I wanted to know how loudspeakers are able to play so many different sounds at the same time. Like, in a song we can hear the voice of the singer and all the musical instruments at the same time. The sounds come from the speaker at the same time. How is the speaker even able to do it?
Thanks.
You use different speakers in different systems and even different serial and parallel configurations; that's one of the reasons there are different impedance values. 8 Ohm speakers are the standard for home, while 4 ohm are usually found in car audio systems.
If a lower impedance loudspeaker generally has better dynamic range and can achieve louder volumes, why do we still see 6, 8 or even 16 ohm speakers? Shouldn't we be "progressing" toward more efficient speakers with lower impedance?
While yes, the benefit of 4 ohm speakers is that the increased current means they have a wider dynamic range, they will be harder on the amplifier (if the amp is made for 8 ohm) and at higher volumes they will have larger THD (total harmonic distortion.) Essentially the output voltage will be unstable during high power application as the Amp will struggle to supply enough current to drive the load.
Using a 4 ohm speaker on a generic home amplifier that is made for an 8 ohm speaker will draw twice as much power and can cause the amplifier to go into protect mode or even overheat and break.
why do we still see 6, 8 or even 16 ohm speakers?
Different serial and parallel configurations are used to change the load on an amplifier. For example, you can have two 4 ohm speakers in series so that the load will be 8 ohms. Or (common in custom car systems,) you may have two 4 ohm speakers connected in parallel so the load on the amplifier is only 2 ohms, thus doubling the current.
Or in this case, four 8 ohm speakers are connected in series parallel so that the total impedance is only 8 ohms.
Are higher impedance speakers merely a product of backward-compatibility?
No they have their place, from allowing different speaker configurations, or less wear and tear on amplifiers to improved sound quality.
Using speaker with higher than minimum impedance may improve quality as the Amp will generate more stable voltage and current. Hence the THD will remain lower at higher impedance while the maximum power output by the Amp will be reduced due to higher load impedance.
Loudspeakers have impedances of 8 ohms, 6 ohms or 4 ohms (those are "nominal" or approximate values, because the impedance of a speaker changes all the time with the different frequencies of music
They are also referred to as at rest values, and if you connect a ohm meter to the speaker it should read 4 or 8 etc. ohms. Then if you gently move the speaker that reading will change. If you measure a speaker and it shows a different value than what it is supposed to then it may be defective of blown or at least slightly damaged.
The 3.5mm output of the raspberry Pi is a line level output. It cannot drive a speaker directly. You will need an amplifier. Headphones/Earbuds vary, but are often 32 ohm, with a power rating of half or less watts. Most small speakers are 1/2/4/8 ohms, with a power rating of 1 or more watts. The line level output just can't drive them.
You can get a simple amplifier premade, or use a audio amplifier chip like the LM386 or TPA2080D1 and a few passive components and make your own.
Alternatively, you can buy a dollar store battery powered mp3/ipod speaker and gut it, powering it off one of the Raspberry's voltage output pins.
Best Answer
The real answer has nothing to do with how speakers work, but the fact that sound waves add in air. When you are listening to a live performance with a singer and instruments, you hear them all together then too. Your question about how a speaker can produce such a composite sound is no different from asking how your ear can hear more than one sound at a time.
Think of what a sound wave really is, which is small aternating pressure variations in the air. You can have multiple sound source, but at any one point in the air you have a single function of pressure over time. This pressure function contains the sum of all the pressures variations caused by all the sound sources.
This varying pressure is what your ears measure at two different points in space (since you have two ears). This sound pressure variation is also what a microphone measures and converters to a electrical signal. At any instant, there is a single pressure value, or a single voltage value coming from a microphone.
A speaker simply does the reverse. It receives a single voltage value at any instant, and produces a local air pressure variation accordingly. Those air pressure variations are ideally the same as measured by the microphone when the recording was made. Since the single-valued function of pressure over time contained the sum of all the sound sources that the microphone picked up, the speaker reproduces the same sum of signals. Your ears then hear the same sum of signals, which allows you to hear the singer and multiple instruments at the same time, just as you would if you were there when the music was performed live.