The detection ranges of broadband sounds produced by marine invertebrates are not known. to address this deficiency, a linear array of hydrophones was built in a shallow water area to experimentally investigate the propagation features of the sounds from various sizes of european spiny lobsters (Palinurus elephas), recorded between 0.5 and 100 m from the animals. The peak-to-peak source levels (SL, measured at one meter from the animals) varied significantly with body size, the largest spiny lobsters producing SL up to 167 dB re 1 µpa 2. the sound propagation and its attenuation with the distance were quantified using the array. This permitted estimation of the detection ranges of spiny lobster sounds. Under the high ambient noise conditions recorded in this study, the sounds propagated between 5 and 410 m for the smallest and largest spiny lobsters, respectively. Considering lower ambient noise levels and different realistic propagation conditions, spiny lobster sounds can be detectable up to several kilometres away from the animals, with sounds from the largest individuals propagating over 3 km. Our results demonstrate that sounds produced by P. elephas can be utilized in passive acoustic programs to monitor and survey this vulnerable species at kilometre scale in coastal waters. Passive acoustic monitoring (PAM) of marine species has recently gained attention by biologists and is now used worldwide. This is due to the increased knowledge of animal sound repertoires, and the behavioral contexts in which they are produced 1-3. In addition, the density of seawater enables sounds to propagate over greater distances compared to air 4. Estimating the detection ranges between a particular sound-producing species and a receiver can give crucial information about its spatial distribution in an ecosystem. These calculations rely on the measurements of the source level (SL, i.e. the sound pressure level recorded at 1 m from the source) and the transmission loss (TL, i.e. the attenuation of the sound as it propagates away from the source) of animal sounds underwater. For example, marine mammal sounds can be detected kilometres away in shallow and deep oceans with hydrophones 5-7. Fish also produce sounds in shallow waters that can be detectable from few meters 8,9 to hundreds of meters away 10,11. However, data available on sound propagation and detection ranges for crustaceans are scarce, though crustaceans are known to emit a large diversity of sounds 12-14. Marine arthropods produce sounds that are mostly characterized by broadband pulses, i.e. short transient sounds with a large bandwidth 15-17. Estimating their sound propagation may be challenging as they inhabit shallow coastal waters (at depths below tens of meters). This implies complex sound fields due to physical constraints such as the presence of boundaries created by the water surface and the seabed 18,19 , and it is thus difficult to accurately model sound propagation 20. Until now, detection ranges of crustacean sounds have relied on crude estimations of SLs performed using distant measurements that are then artificially back-propagated to 1 m by using theoretical propagation models 21,22. In addition, some studies have been performed in tanks. Tank experiments are very convenient since distances between receivers and animals can be precisely measured 23. However, tank acoustics are complicated. The relatively small volumes and close boundaries of tanks highly affect sound propagation as well as SL estimates 13,14 ; these tank effects have been largely ignored by most previous studies (as a counter example, see 15 for an experimental illustration on the differences of crustacean sounds recorded in tanks and in situ). Thus, there is a need to combine theory with empirical measurements of site-specific sound propagation