A subwoofer (or sub) is a woofer, or a complete loudspeaker, which is dedicated to the reproduction of low-pitched audio frequencies known as bass. The typical frequency range for a subwoofer is about 20–200 Hz for consumer products, below 100 Hz for professional live sound, and below 80 Hz in THX-approved systems. Subwoofers are intended to augment the low frequency range of loudspeakers covering higher frequency bands. While the term "subwoofer" technically only refers to the speaker driver, in common parlance, the term often refers to a subwoofer driver mounted in a speaker enclosure (cabinet).
The term Scandinavia always includes the three kingdoms of Denmark, Norway, and Sweden. The remote Norwegian islands of Svalbard and Jan Mayen are usually not seen as a part of Scandinavia, nor is Greenland, an overseas territory of Denmark. However, the Faroe Islands, also a Danish overseas territory, are sometimes included, as sometimes are Iceland, Finland, and the Finnish autonomous region of the Åland Islands, because of their historical association with the Scandinavian countries and the Scandinavian peoples and languages.
This looser definition almost equates to that of the Nordic countries. In Nordic languages, only Denmark, Norway and Sweden are commonly included in the definition of Scandinavia.
The meaning of a spiritual retreat can be different for different religious communities. Spiritual retreats are an integral part of many Hindu, Buddhist, Christian and Sufi (Islamic) communities.
In Hinduism and Buddhism, meditative retreats are seen by some as an intimate way of deepening powers of concentration and insight.
Retreats are also popular in Christian churches, and were established in today's form by St. Ignatius of Loyola (1491-1556), in his Spiritual Exercises. Ignatius was later to be made patron saint of spiritual retreats by Pope Pius XI in 1922. Many Protestants, Catholics and Orthodox Christians partake in and organize spiritual retreats each year.
Meditative retreats are an important practice in Sufism, the mystical path of Islam. The Sufi teacher Ibn Arabi's book Journey to the Lord of Power (Risālat al-Anwāar) is a guide to the inner journey that was published over 700 years ago.