3 ms·

> Classical music performed in large concert halls is one surprising candidate Dumb question: what's emitting these frequencies in an orchestra?

elmomle 4y ago
I imagine it's the space itself resonating more than anything else, being excited by higher-frequency harmonics.
WorkerBee28474 4y ago
Instruments that play <= 40Hz (E1) include double bass (either standard or with C extension), bass clarinet, and contrabass clarinet. Percussion also generates frequencies under 40Hz.
- mrob 4y ago
  And percussion generates sharp transients, which require frequencies below the steady-state fundamental frequency to be reproduced accurately: https://en.wikipedia.org/wiki/Uncertainty_principle#Signal_processing https://en.wikipedia.org/wiki/Uncertainty_principle#Signal_p...
- mechanical_bear 4y ago
  Also octobasse and subcontrabass saxophone…although most people won’t get a chance to actually hear those in person.
- Nition 4y ago
  Piano too if there is one. The fundamental frequency of the low A is 27.5Hz. A Bosendorfer Imperial grand piano goes down to C0, 16.4Hz. If there's a pipe organ with 64' pipes you can hit 8Hz. Not many of those though.
  - aidenn0 4y ago
    Plenty of organs go below 20Hz though, and even an otherwise good sound system starts to struggle around 40Hz if it's not built specifically for playing such notes.
  - Blackthorn 4y ago
    Dumb question but how is the piano capable of generating these frequencies? I thought the strings couldn't get nearly long enough and the low frequencies that you heard from piano were just psychoacoustics.
    - quercusa 4y ago
      The bass strings are wound with copper wire so that the mass is much higher and the resonant frequency much lower.
      - deleted 4y ago
        [deleted]
    - Nition 4y ago
      The amount of space needed for a certain frequency in air is different to the length needed for that same frequency in a wire. It might help to see the formula, which is: Frequency = sqrt(tension/(mass / length)) / (2 * length) So length, tension, and mass are all factors. Modern upright pianos also string the bass strings diagonally to give them a bit of extra length. Having said all that, the same bass notes on longer pianos that can fit longer strings sound more sonorous. I'm not sure exactly why that is. For an extreme example see for instance the Alexander Piano[0], or the Klavins 370[1]. [0] https://youtu.be/PcP8UMgsmFo?t=132 https://youtu.be/PcP8UMgsmFo?t=132 [1] https://www.youtube.com/watch?v=LPGw-Va5xPU https://www.youtube.com/watch?v=LPGw-Va5xPU
      - dehrmann 4y ago
        I can almost imagine seeing the low bass string on the longest piano vibrating. The frequency is so low you can pick hear the peaks and valleys.
crazygringo 4y ago
I'd say timpani drums, tubas, largest/lowest pipes on an organ (if the hall has one), and double bass. Contrabassoon, the lowest notes of a piano. Other percussion like a gong. Basically, by necessity, whatever the largest instruments are in diameter or length. And then it's all being amplified by some mutual resonance with each other and possibly other physical structures like the floor.

elmomle 4y ago

I imagine it's the space itself resonating more than anything else, being excited by higher-frequency harmonics.

WorkerBee28474 4y ago

Instruments that play <= 40Hz (E1) include double bass (either standard or with C extension), bass clarinet, and contrabass clarinet. Percussion also generates frequencies under 40Hz.

mrob 4y ago
And percussion generates sharp transients, which require frequencies below the steady-state fundamental frequency to be reproduced accurately: https://en.wikipedia.org/wiki/Uncertainty_principle#Signal_processing https://en.wikipedia.org/wiki/Uncertainty_principle#Signal_p...
mechanical_bear 4y ago
Also octobasse and subcontrabass saxophone…although most people won’t get a chance to actually hear those in person.
Nition 4y ago
Piano too if there is one. The fundamental frequency of the low A is 27.5Hz. A Bosendorfer Imperial grand piano goes down to C0, 16.4Hz. If there's a pipe organ with 64' pipes you can hit 8Hz. Not many of those though.
- aidenn0 4y ago
  Plenty of organs go below 20Hz though, and even an otherwise good sound system starts to struggle around 40Hz if it's not built specifically for playing such notes.
- Blackthorn 4y ago
  Dumb question but how is the piano capable of generating these frequencies? I thought the strings couldn't get nearly long enough and the low frequencies that you heard from piano were just psychoacoustics.
  - quercusa 4y ago
    The bass strings are wound with copper wire so that the mass is much higher and the resonant frequency much lower.
    - deleted 4y ago
      [deleted]
  - Nition 4y ago
    The amount of space needed for a certain frequency in air is different to the length needed for that same frequency in a wire. It might help to see the formula, which is: Frequency = sqrt(tension/(mass / length)) / (2 * length) So length, tension, and mass are all factors. Modern upright pianos also string the bass strings diagonally to give them a bit of extra length. Having said all that, the same bass notes on longer pianos that can fit longer strings sound more sonorous. I'm not sure exactly why that is. For an extreme example see for instance the Alexander Piano[0], or the Klavins 370[1]. [0] https://youtu.be/PcP8UMgsmFo?t=132 https://youtu.be/PcP8UMgsmFo?t=132 [1] https://www.youtube.com/watch?v=LPGw-Va5xPU https://www.youtube.com/watch?v=LPGw-Va5xPU
    - dehrmann 4y ago
      I can almost imagine seeing the low bass string on the longest piano vibrating. The frequency is so low you can pick hear the peaks and valleys.

crazygringo 4y ago

I'd say timpani drums, tubas, largest/lowest pipes on an organ (if the hall has one), and double bass. Contrabassoon, the lowest notes of a piano. Other percussion like a gong. Basically, by necessity, whatever the largest instruments are in diameter or length. And then it's all being amplified by some mutual resonance with each other and possibly other physical structures like the floor.