Auditory Feedback: Definition and Examples
Auditory feedback refers to the sound(s) you hear after you perform an action. For example, if you drop a pencil, the auditory feedback you receive is the clattering sound of the pencil hitting the floor. Auditory feedback is critical for speech production.
Speakers use auditory feedback to guide their speech, changing their articulation and acoustic output online to correct for apparent speech errors. Evidence for the use of auditory feedback during the online control of speech articulation comes from studies that experimentally manipulate feedback in real time, introducing intermittent discrepancies between produced and observed vowel formants.
When infants are learning to speak, they listen to the people around them and try to imitate the sounds they hear. As they try to imitate speech sounds, they alter the sounds they make based on the auditory feedback they receive (the sounds they hear themselves making).
Experiment design
The Role of Auditory Feedback in Speech Motor Control
In some models of speech motor control, such as Directions Into Velocities of Articulators, feedback gains are also thought to drive changes in feedforward control over time. A number of factors have been proposed to account for variation of these gains across individuals, including auditory and somatosensory acuity, variation in the balance between auditory and somatosensory systems, production variability, and the presence of neurological disorders such as stuttering, Parkinson's disease, and cerebellar ataxia.
Critically, evidence from nonspeech motor control suggests feedback gains may be more malleable than is often assumed in speech research. For example, when participants are given altered visual feedback about their hand position during a reach, the magnitude of their compensation for this perturbation is modulated by the reliability of the visual feedback. That is, compensation is largest when the feedback is most reliable-a single dot representing their hand-and smaller when it is less reliable-a cloud of dots centered at the position of their hand.
These results show that the online compensation for sensory errors is not a fixed characteristic of the sensorimotor control system, but rather takes into account the reliability of the sensory signal, even when that reliability varies across repetitions of a movement. Moreover, there is evidence from reaching tasks that people monitor their history of sensory errors over time to generate estimates of the reliability of sensory signals.
In speech, evidence for similar effects of sensory reliability is limited. However, there is some evidence that the control of vocal pitch is consistent with an optimal sensory system, which has higher gains for more reliable signals. When somatosensory feedback is partially blocked by the application of topical anesthetic to the vocal folds, compensation for auditory pitch perturbations increases, as the auditory signal is now relatively more reliable. Separately, pitch perturbations that are unpredictable in magnitude or direction lead to larger compensatory responses than predictable perturbations; that is, the nature of previously encountered auditory errors can affect the magnitude of compensation. This suggests the vocal sensorimotor system monitors a history of sensory errors, as in reaching.
Here, we examine how the reliability of auditory feedback signals affects feedback control during speech production. Specifically, we test how repeated exposure to auditory errors-that is, added feedback noise in the form of small alterations to formant frequency-affects the magnitude of compensation for subsequent auditory feedback perturbations.
In separate sessions, participants were consistently exposed to small, random perturbations of their vowel formants (noisy session) or received veridical auditory feedback (veridical session). We subsequently measured the magnitude of compensation for intermittent, unpredictable auditory perturbations. This design allows us to test for changes in compensation as auditory reliability decreases. Our results provide evidence that compensation magnitude is reduced after exposure to unreliable feedback, consistent with a downweighting of auditory feedback caused by a decrease in its reliability.
Applications of Auditory Feedback
Auditory feedback devices are usually made up of a mouthpiece that is connected to an earpiece by tubing. When a student speaks into the mouthpiece of an auditory feedback device, the student’s voice is channeled directly into his/her ear. Auditory feedback devices can be useful for students in several ways:
- Develop phonemic-awareness skills. Phonemic awareness is the knowledge that words are made up of sounds, and that sounds can be added, deleted, or changed in words to make new words. Strong phonemic-awareness skills are linked to later success with reading.
- Build reading skills. As a student hears him/herself reading aloud, he/she is able to develop better reading skills. The auditory feedback a student receives from hearing his/her voice when reading aloud can help to improve reading accuracy, fluency, and rate.
- Read aloud without disturbing others with a quieter volume.
- Minimize the effects of background noise. When students are grouped together, as they are in a classroom setting, background noise is unavoidable.
- Enhance auditory processing abilities. Auditory processing refers to our ability to make sense out of the sounds we hear.
- Improve articulation.
Musical training is increasingly recognized as a useful tool to enhance motor and cognitive functions as well as QoL in patients with stroke. Musical activities provide a multimodal experience that requires the simultaneous activation of different brain areas. These areas are involved in sensory-motor function, auditory processing, emotional processing, and cognitive functions such as memory and attention. When playing a musical instrument, the immediate auditory feedback provided by the instrument is used to adjust future movements and reinforce motor learning. Musical training can provide enjoyment, stress relief, and distraction from negative cognitive states and from physical effort. Moreover, learning to play an instrument involves acquiring a new skill set enabling patients to gain a sense of competence.
Computer vision technology-based face mirroring system providing mirror therapy for Bell’s palsy patients. Auditory feedback was widely used in virtual reality technology for visual fidelity perception and better immersion. In our study, the enunciation provided intrinsic combinations consisting of speech paired auditory feedback and visuo-proprioceptive feedback for BP, where the effect on facial embodiment was investigated for the first time. A possible interpretation of this finding is that the combination of speech during facial motion may enhance attention, which requires more cognitive process and extends the immersion.
Auditory feedback devices
The WSs identified in this review made use of various visualization devices with different characteristics in terms of immersion, field of view (FOV) and stereoscopy. Only a few examples of WSs (n = 14) found in the literature considered the design of auditory displays. Most of these foresaw the employment of auditory cues in response to the user’s interaction with objects. In some cases, auditory feedback was used to provide instructions or motivational messages during the training. A few solutions included music playing in background, sounds marking the beginning and the end of the exercise or stereoscopic sounds aimed at increasing realism and engagement.