This document describes a system for determining positioning of an intubation tube in a patient. The system can include a first acoustic sensor configured to be disposed to listen to one of a lung and a stomach of the patient and to provide a first signal. The system includes a signal processing unit, coupled to the first acoustic sensor, configured to analyze spectral components of the first signal and determine whether a frequency of the spectral components of the first signal are characteristic of sounds induced by ventilation via the intubation tube of airflow to the lung or the stomach of the patient.