In the late 1960s JBL introduced two monitors which helped secure them pre-eminence in the industry. The 4320 was a direct competitor to the Altec 604 but was a more accurate and powerful speaker and it quickly made inroads against the industry standard. However, it was the more compact 4310 that revolutionized monitoring by introducing the idea of close or "nearfield" monitoring. (The sound field very close to a sound source is called the "near-field." By "very close" is meant in the predominantly direct, rather than reflected, sound field. A near-field speaker is a compact studio monitor designed for listening at close distances (), so, in theory, the effects of poor room acoustics are greatly reduced.)