Acoustic output devices

An acoustic output device comprising:

• a bone conduction acoustic assembly used to generate a bone conduction sound wave;
• an air conduction acoustic assembly used to generate an air conduction sound wave;
• and
• a housing used to accommodate at least a portion of elements of the bone conduction acoustic assembly and the air conduction acoustic assembly, the housing including a first chamber and a second chamber, the first chamber being used to accommodate at least a portion of the bone conduction acoustic assembly, the housing being provided with a sound outlet communicated with the second chamber, the air conduction sound wave being transmitted to an outside of the acoustic output device via the sound outlet, wherein
• the housing is further provided with at least one pressure relief hole communicated with the first chamber, the at least one pressure relief hole includes a first pressure relief hole and a second pressure relief hole, the first pressure relief hole is provided farther away from the sound outlet than the second pressure relief hole, and an effective area of an outlet end of the first pressure relief hole is larger than an effective area of an outlet end of the second pressure relief hole;
• a frequency response curve of the air conduction sound wave having at least one resonance peak, a peak resonance frequency of the at least one resonance peak being greater than or equal to 1 kHz, wherein
• the housing is further provided with at least one tuning hole communicated with the second chamber, and the peak resonance frequency of the at least one resonance peak when the at least one tuning hole is in an open state is shifted to high frequency compared to the peak resonance frequency of the at least one resonance peak when the at least one tuning hole is in a closed state;
• the housing includes a first side wall and a second side wall disposed on opposite sides of the bone conduction acoustic assembly, and the at least one tuning hole includes a first tuning hole, the sound outlet and the first tuning hole being disposed on the first side wall and the second side wall, respectively;
• the housing further includes a third side wall and a fourth side wall connecting the first side wall and the second side wall and spaced apart from each other, and the at least one tuning hole further includes a second tuning hole, the second tuning hole being provided on the third side wall or the fourth side wall;
• an effective area of an outlet end of the first tuning hole is larger than an effective area of an outlet end of the second tuning hole;
• or
• an actual area of the outlet end of the first tuning hole is larger than an actual area of the outlet end of the second tuning hole.