Final answer:
Nasal and oral transducers are key instruments used for measuring air pressures and airflows from the nasal and oral cavities during speech, offering a non-invasive alternative to catheter-based methods typically used in surgery or intensive care.
Step-by-step explanation:
The instruments of choice for measuring the relative air pressures and airflows emitted simultaneously from the nasal and oral cavities during speech are nasal transducers and oral transducers. Nasal and oral transducers are non-invasive alternatives to catheters for monitoring air pressures, which additionally can provide valuable information in the study of speech patterns and disorders.
The reference to invasive pressure measurements with catheters provides a context where such devices are used—these are usually only monitored during surgery or for patients in intensive care with the help of qualified health care workers.
Frequently used in various applications, including as air speed indicators in aircraft, similar devices can be adapted for medical use to aid speech therapists, clinicians, and researchers in assessing and treating speech-related conditions.