Spoken English may sometimes cause us to face a peculiar problem in respect of the reception and the decoding of auditive signals, which might lead to mishearings. Risen from erroneous perception, from a lack in understanding the communication and an involuntary mental replacement of a certain element or structure by a more familiar one, these mistakes are most frequently encountered in the case of listening to songs, where the melodic line can facilitate the development of confusion by its somewhat altered intonation, which produces the so called mondegreens. Still, instances can be met in all domains of verbal communication, as proven in several examples noticed during classes of English as a foreign language (EFL) taught to non-philological subjects. Production and perceptions of language depend on a series of elements that influence the encoding and the decoding of the message. These filters belong to both psychological and semantic categories which can either interfere with the accuracy of emission and reception. Poor understanding of a notion or concept combined with a more familiar relation with a similarly sounding one will result in unconsciously picking the structure which is better known. This means ‘hearing’ something else than it had been said, something closer to the receiver’s preoccupations and baggage of knowledge than the original structure or word. Some mishearings become particularly relevant as they concern teaching English for Specific Purposes (ESP). Such are those encountered during classes of Business English or in English for Law. Though not very likely to occur too often, given an intuitively felt inaccuracy – as the terms are known by the users to need to be more specialised -, such examples are still not ignorable. Thus, we consider they deserve a higher degree of attention, as they might become quite relevant in the global context of an increasing work force migration and a spread of multinational companies.