A sound-filtering device can include an entry port that receives sound from an environment when the device is coupled to an ear of a user. The device can further include an exit port that delivers sound that has passed through the device to the ear of the user. The device can further include a channel extending between the entry port and the exit port to define a path along which sound travels from the entry port to the exit port. The device can also include a side port in fluid communication with the channel and a resonant chamber offset from the path defined by the channel and in fluid communication with the channel via the side port. The resonant chamber can attenuate at least a portion of any sound passing through the channel that is within a band of frequencies narrower than a full audible spectrum of the user.
