Abstract: This invention relates to a method and a microprocessor-based apparatus for directly measuring the noise using a nuisance index (L.sub.DI) bound to two physical parameters of the noise: the average energy level (L.sub.E) and the fluctuation level of the noise.The apparatus is comprised of a microphone (M) connected to a pre-amplifier (1) and a detecting unit (2) controlling an analogical-to-digital converter (3) associated to a time (4) feeding a signal to a digital filter (5) and at the same time to one input of a comparator (6). The filter (5) feeds the filtered signal to an integrator (7) supplying the parameter (L.sub.E) and simultaneously to the second input of comparator (6) which supplies the parameter (L.sub..phi.) through counter (8) associated to a trimmer (10). Parameters (L.sub.E) and (L.sub..phi.) are indicated in block (9) of the display.

Abstract: A seismic source consists of an electroacoustic transducer having a metallic structure, shaped like an empty round paraboloid (1) closed at the base by means of an elastic diaphragm and filled with a proper liquid. Around the focus of the paraboloid two main electrodes (5) are set and an auxiliary electrode (6) is put between the first ones. The main electrodes (5) are connected to a set of capacitors (C.sub.o) supplied by a high-voltage power supply (HT). One of the main electrodes (5b) and the auxiliary electrode (6) are connected to a trigger pulse generator (EHT) driven by a remote control (4) via a synchronization pulse generator (3). The discharge between the main electrodes (5) primed by a preliminary spark, generates an acoustic pulse through the liquid medium of the transducer on the ground where the paraboloid (1) is engaged. So the transducer generates seismic waves utilized for shallow prospecting both on land and underwater.