a device for monitoring the travel of yarn - like structures at a textile machine comprises a cantilever member vibrating in a flexural mode when excited by a traveling yarn which is in contact with the upper or free end of said cantilever member . the lower end thereof is rigidly connected or integral with a rigid base member having the effect of a seismic mass when exposed to shock or vibration . moreover , soft elastic material is provided to prevent transfer of such shock or vibration from the textile machine to the cantilever member . a mechano - electrical transducer element , e . g ., a piezoelectric element , is comprised by or coupled with the cantilever member for generating an electrical yarn travel signal . a casing may be provided for protecting said cantilever member against ambient noise and other undesired actions acting from outside the casing .