The present invention relates to the testing of leather, in particular the testing of leather for grain surface cracking. Leather is tested for its strength and grain distension in order to determine its suitability for a particular use, such as shoe manufacture. There is described a method for the determination of physical characteristics of a leather sample (10), the method including the steps of applying a physical procedure to the sample of leather; and monitoring and analysing audible acoustic emissions from the sample. There is also described an apparatus adapted for use in such method comprising means for applying a physical procedure to a sample of leather (10) and an acoustic sensor (12). Typically, the acoustic sensor comprises at least one transducer, such as a microphone, and monitors acoustic emissions in the range of 200 Hz to 22kHz. For certain analyses, the acoustic sensor comprises an annular array comprising a plurality of transducers each mounted equidistantly from the means applying the physical procedure.