Method for a device for tracking a fundamental frequency of a voice signal, wherein the device contains a sampling apparatus attached to an endoscope, a calculation apparatus and a serial interface that connects the calculation apparatus and the sampling apparatus, wherein the sampling apparatus comprises a microphone that is positioned close to the glottis of a test subject and records a voice signal of the test subject, wherein the method comprises the steps: (a) sampling the voice signal of the test subject over a predetermined time interval on the sampling apparatus, by way of which sampling data of the voice signal are obtained, wherein the predetermined time interval comprises a particular number of oscillations of the voice signal, and triggering step (b) when a particular number of sample values have been acquired by sampling the voice signal over the predetermined time interval, (b) forming a data packet from the sampling data on the sampling apparatus, wherein the data packet contains the particular number of sample values of the voice signal, (c) transmitting the data packet from the sampling apparatus to the calculation apparatus via the serial interface, (d) calculating a fundamental frequency of the voice signal using the sampling data contained in the data packet on the calculation apparatus, and transmitting the calculated fundamental frequency to the sampling apparatus via the serial interface, (e) setting a timer based on the fundamental frequency transmitted by the calculation apparatus, and (f) outputting a trigger signal when the timer expires, wherein steps (a) to (d) are repeated a particular number of times, step (e) is performed after the timer expires, and step (d) is performed asynchronously with respect to steps (a) to (c), (e) and (f), and wherein steps (a) to (c), (e) and (f) are performed by a processor of the sampling apparatus, which processor executes a program stored in a memory of the sampling apparatus, and wherein step (d) is performed by a processor of the calculation apparatus, which processor executes a program stored in a memory of the calculation apparatus. (a) sampling the voice signal of the test subject over a predetermined time interval on the sampling apparatus, by way of which sampling data of the voice signal are obtained, wherein the predetermined time interval comprises a particular number of oscillations of the voice signal, and triggering step (b) when a particular number of sample values have been acquired by sampling the voice signal over the predetermined time interval, (b) forming a data packet from the sampling data on the sampling apparatus, wherein the data packet contains the particular number of sample values of the voice signal, (c) transmitting the data packet from the sampling apparatus to the calculation apparatus via the serial interface, (d) calculating a fundamental frequency of the voice signal using the sampling data contained in the data packet on the calculation apparatus, and transmitting the calculated fundamental frequency to the sampling apparatus via the serial interface, (e) setting a timer based on the fundamental frequency transmitted by the calculation apparatus, and (f) outputting a trigger signal when the timer expires,