Andreeww
100+ Head-Fier
What happens if I get the polarity reversed. Does it damage my phones? Or does it affect sound? How?
Help! What's happens if I get the polarity of IEMs wrong?
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PleasantSounds
Headphoneus Supremus
Nothing should happen to your phones.
The result will be an incoherent stereo image. Most instruments sitting on the far left and right and what's between cannot be located.
The result will be an incoherent stereo image. Most instruments sitting on the far left and right and what's between cannot be located.
CochlearConcept
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That's a good question for headphones, as you won't get the same superposition / interference patterns that you get with loudspeakers in sound field or free field.
There's the question of absolute phase and relative phase, too. Relative phase refers to one ear's monitor being in phase (homophasic) or out of phase (antiphasic) with opposite ear's earpiece. In a sound field, anti-phase, = 180 degrees out of phase, results in cancellation of low frequencies (destructive interference). In the case of earphones, the perceived consequences to music aren't as well documented. There's literature in audiometry alluding to speech signals under antiphasic earphones. The effect is very real, so you at least want the relative phase of earphones to match.
You won't damage your headphones or your hearing based on phase "correctness". It is often difficult to ascertain the absolute phase of a signal because you have to know the whole audio chain (inverting and non-inverting gain stages). For example, does the compression from a kick drum result in compression wave from earphone, or does the earphone membrane move in concert (absolute phase) with original source signal?
At very least, you do want the earphones to work in concert so the L and R are matched in relative phase. Unless you have separate L and R connections (i.e., no common ground connect between earphones), the headphones should always be matched to one another... unless manufacturer made a boo-boo.
Best,
CochlearConcept
There's the question of absolute phase and relative phase, too. Relative phase refers to one ear's monitor being in phase (homophasic) or out of phase (antiphasic) with opposite ear's earpiece. In a sound field, anti-phase, = 180 degrees out of phase, results in cancellation of low frequencies (destructive interference). In the case of earphones, the perceived consequences to music aren't as well documented. There's literature in audiometry alluding to speech signals under antiphasic earphones. The effect is very real, so you at least want the relative phase of earphones to match.
You won't damage your headphones or your hearing based on phase "correctness". It is often difficult to ascertain the absolute phase of a signal because you have to know the whole audio chain (inverting and non-inverting gain stages). For example, does the compression from a kick drum result in compression wave from earphone, or does the earphone membrane move in concert (absolute phase) with original source signal?
At very least, you do want the earphones to work in concert so the L and R are matched in relative phase. Unless you have separate L and R connections (i.e., no common ground connect between earphones), the headphones should always be matched to one another... unless manufacturer made a boo-boo.
Best,
CochlearConcept
Andreeww
100+ Head-Fier
OK let me answer my own question. The performance of the IEMs decreases, especially bass and resolution.
CochlearConcept
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Hi,
That would make a lot of sense if you're using an IEM during a performance (that is, as an actual live-music monitor, not an earphone playing recorded muzak). In one polarity, you'd have a rough equivalent of feedforward noise cancellation. The IEM only provides so much passive attenuation, so sound from outside sources will mix with "same" sound being produced by inner ear speaker or speakers. The sounds can sum or subtract, depending on frequency. Pass-through phase (deg or rad) as well as attenuation (dB) is frequency dependent. Anyway, live monitoring would be a lot more sensitive to phase reversal than listening to recorded music. But it's awesome you answered your own question: Listening beats theory or measurements, though the latter can help predict a good or bad designs. I've seen peer-reviewed research on the psychoacoustical effects of phase shifts under earphones, but most studies used laboratory stimuli (e.g. tones) and not complex signals such as music. I'm a proponent of real-world listening, which often precludes direct or simple measurements. The ear-brain system is complex and sensitive to phenomenon that are hard to measure. Great to learn something new: Phase correctness (PC) makes big difference.
Thanks for sharing your observation,
CochlearConcept
That would make a lot of sense if you're using an IEM during a performance (that is, as an actual live-music monitor, not an earphone playing recorded muzak). In one polarity, you'd have a rough equivalent of feedforward noise cancellation. The IEM only provides so much passive attenuation, so sound from outside sources will mix with "same" sound being produced by inner ear speaker or speakers. The sounds can sum or subtract, depending on frequency. Pass-through phase (deg or rad) as well as attenuation (dB) is frequency dependent. Anyway, live monitoring would be a lot more sensitive to phase reversal than listening to recorded music. But it's awesome you answered your own question: Listening beats theory or measurements, though the latter can help predict a good or bad designs. I've seen peer-reviewed research on the psychoacoustical effects of phase shifts under earphones, but most studies used laboratory stimuli (e.g. tones) and not complex signals such as music. I'm a proponent of real-world listening, which often precludes direct or simple measurements. The ear-brain system is complex and sensitive to phenomenon that are hard to measure. Great to learn something new: Phase correctness (PC) makes big difference.
Thanks for sharing your observation,
CochlearConcept
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